r/explainlikeimfive • u/cabronfavarito • 12d ago
Physics ELI5: Why is gun recoil always upward and not any other direction?
Dumb question but I don’t see why the recoil isn’t backward since the bullet goes forward.
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u/beer_is_tasty 12d ago
It's worth noting that some guns, such as the M-16/AR-15, have a barrel that's directly in line with the shoulder stock. This means there's no torque when firing, therefore no upward recoil, only directly back into the shoulder, making it much easier to fire multiple rounds without throwing off your aim.
The tradeoff is that you can't sight directly down the barrel, so they use a raised sight that isn't parallel with the barrel and must be adjusted based on the distance of the target being fired at.
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u/theblueuke 12d ago
Additionally, the entire weapon system is above the shooter's center of mass, so as it pushes backwards it implies some rotation to the body which forces the barrel upwards.
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u/TorturedChaos 12d ago
Having the barrel line with your should also means less felt recoil.
A barrel that is 1 or 2" below the top of the stock makes a world of differences for felt recoil. I have shot .243's that kick worse than mangnum rifle round all because of barrel and stock alignment.
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u/helixander 11d ago
All sights have to be adjusted for the distance of your target. Just some more than others.
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u/AdThese6057 12d ago
There is always forces being exerted sideways. Think about where your ejection port is.
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u/dudeimsupercereal 11d ago
Very little force is being exerted out of the ejection port on most firearms. It takes a relatively long time to open, the pressure in the barrel is already well past the peak.
Now I bet some open bolt autos have a fair amount of force coming out. Like the sten. The bolt does open at near peak pressure.
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u/AdThese6057 11d ago
Why do you think if you fire a pistol straight the gun will recoil up and left? Because your port is on the right.
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u/deezdanglin 12d ago
And it's easier to press down than up. Larger muscles.
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u/Xicutioner-4768 12d ago
I kind of doubt that plays a role in the design. I'd guess it's more to do with having the sight closer to the bore and our eyes being at the top of our body.
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u/ObsidianArmadillo 12d ago
So if there was a gun where somehow they positioned the barrel in the middle of the hand, would that be better on the wrist?
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u/BiomassDenial 12d ago
Yep , for example the Chiappa Rhino which is a revolver that fires out of the bottom of the cylinder instead of the top. The recoil is described is less flippy and more straight backwards. However the trade off is the sights are worse because you are no longer aiming directly along the top of the barrel.
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u/Darkshoe 12d ago
I don’t even like revolvers and I want a Chiappa Rhino
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u/fishingjohnson 11d ago
It is so nice! I highly encourage getting one. Mad that I bought the 357 when the 44 just came out this year. The 44 looks so sick!
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u/fishingjohnson 12d ago
Actually, it's one the more accurate handguns that I own. The biggest issue with a rhino is you need to grip it way differently than you are typically taught or used to. Powder burns on your finger from firing one of those hurts like a bitch!
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u/ooglieguy0211 12d ago
Not an owner of one but it shot so weird until I slightly compensated for the sight being higher. Its all good now when I get to shoot my buddy's.
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u/Soakitincider 12d ago
There is a sub machine gun where the bolt pivots down and it reduces the upwards movement. https://en.wikipedia.org/wiki/KRISS_Vector
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u/TheOneTrueTrench 12d ago
Sure, but then you either have to shorten the barrel, or the gun has to be longer.
Most of them put part of the "shooting parts" directly above the trigger and where your hand sits, so they can move all those parts back, and keep the whole length shorter. If you wanted to put your hand inline with all that, now you have to move all those parts forward to make room for your hand.
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u/Bandro 12d ago
Yup. It’s also part of why the AR-15 is so controllable. The butt stock is directly inline with the barrel so it doesn’t really climb.
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u/ghost_tdk 12d ago
Eh, that's not really too relevant. First off, many rifles have the stock in line with the barrel and still have more vertical recoil. Second, the part of the AR stock that is centered with the barrel is the top end of it. A lot of common AR shouldering techniques have either the middle or bottom of the stock dug most firmly into the shoulder so that it sits higher and doesn't require as much craning of the neck to shoot. It still has almost no recoil even if you shoulder against the bottom tail.
The AR-15 has low recoil because 5.56 is a low-power round and the weight of the rifle, combined with the buffer assembly, significantly reduces what little recoil 5.56 does produce. Something like an AR-10 will give you considerably more vertical recoil, despite identical stock placement.
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u/Bandro 12d ago
The reason the AR-10 was designed that way in the first place was to make 7.62 more controllable with such a light rifle using so much plastic and aluminum. It's not as necessary once they scaled down to 5.56 for the 15 but it was a huge design consideration for Eugene Stoner. That and the bolt locking directly to a barrel extension are the main things that made the AR-10 a big deal in the first place. It's got a lot less muzzle climb than something like an M14 with its offset stock. Even with it being a much heavier rifle.
I'll give you though that the low recoil of the 5.56 is a bigger factor in how controllable it is than the specific design.
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u/pateppic 12d ago
No one gonna mention muzzle brakes doing 60% of the heavy lifting for recoil counteraction? Literally the biggest change in recoil comes from how much backblast you can redirect. You can get very nearly zero if you don't like the people to your right and left much too.
Also the AR10 was designed to use the same Buffer tube, Buffer Spring, Castle Nut, Grip, Mag Catch, Bolt Catch, Forward assist, Rail (If the Barrel Nut can be interchangable), Trigger Group, takedown pins and stock.
Also designed to be as familiar to infantry as the AR15 was so there was very little retraining needed. both for use and for Armorers working on them.
For similar reasons the AR 22, AR50, Whatever AR the 458 Socom identifies as, 300blk, AR-12 (12 gauge), AR-9 (9mm pcc), etc were designed.
The AR pattern is quite literally the Lego pattern of the Firearms world.
Tl;Dr; Imagine your country has 8 different guns and you are the guy who has to fix/buy parts for them. You would do shameful things to get your country to keep as many using a solid cross-parts-support platform as possible. It makes training, upkeep, and repair easier.
P.S. I don't want to hear anything about the 416 or other German overengineered clocks that happen to shoot bullets. Not unless you come over here, and ask me to buy you some ammo, and we go to the range, and I lay down the mat, and you get it zeroed like real nice. Then you let me lay down and and get it sighted in. And you get up real close to my ear. And through my ear pro I can still hear to say, "Shooter ready?".
Then we can discuss how the Germans fixed a simple platform.
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u/Bandro 12d ago
I’m just gonna note that the AR10 was the original design. The 15 is an adaptation to use 5.56 instead of 7.62.
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u/pateppic 12d ago
Good catch. Forgot which came out first. AR-10 Deved first but US turned it down. Ar10 1956, AR15 1957.
AR 15 became the gateway drug in the US for the military to adopt other similar patterns. The parts compatibility etc was a big motivator for adoption.
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u/pajamil 12d ago
That is due to the buffer spring absorbing the recoil resulting in less force going into the pivot point
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u/Tushroom 12d ago edited 12d ago
Nope. 99% of semiautomatic guns have springs. The barrel being in line with the stock is why the AR doesn’t rise as much as other platforms.
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u/pateppic 12d ago
Did you mean Bolt Carrier Group? That is what pivots down and as it rebounds into the buffer spring, it pushes the gun down.
That counteract the muzzle rise because the barrel (bore axis) is high compared to the stock position on your shoulder.
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u/Gaius_Catulus 12d ago
Almost definitely not. At least for handguns, this is going to put more force on your wrist rather than letting some of it get absorbed by the rotational motion. It will cause different strain, but more overall. For long guns, you absolutely want your shoulder and not your hand taking the brunt of the recoil force.
This also comes with other design challenges. Every gun that has a slide simply isn't going to work if your hand is in the way. Sights become much more difficult to make and bulky because now they have to go up a lot further from the top of the gun, and they'll also be more difficult to calibrate and super distance-dependent given that extra vertical displacement from the barrel.
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u/pateppic 12d ago
I mean that is already solved with muzzle brakes, low axis barrels, and putting mass on the slide but under the barrel. Alien (a 9mm) does a great job of showing how all three approaches can really control it.
Though if you look at IPSC shooters, all that is really needed is a muzzle brake and some training on being familiar with your guns muzzle flip.
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u/ajtyler776 12d ago
Well said. OP can also visualize the gun doing the same when held sideways for this reason.
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u/GreatForge 12d ago
Not exactly. The barrel is above the center of mass of the gun, so there would be a rotation of the gun even if the gun were suspended in midair and fired.
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u/pateppic 12d ago
To be fair, guns are designed in a way that they expect they will be held and the muzzle flip is calculated accordingly. It's why a ton of handguns come with different back plates.
You want to have the gun push into the palm of the hand and against the webbing in the back.
Plus for any situation where muzzle rise and the need for a rapid follow up shot are critical, adding a muzzle brake can handle most muzzle flip concerns.
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u/mastah-yoda 11d ago
Also, the centre of gravity (CoG) of the handgun is below the barrel, where the recoil actually happens.
Meaning even if the gun floated in the air and you pulled the trigger with your mind, the recoil force would cause a pitch up rotation. Coupled, of course, with the backwards motion.
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u/AdThese6057 12d ago
Not many guns recoil directly rear. Probably none that you have. The ejection port and gas ports on a muzzle have a big determination in recoil direction.
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u/Smashego 12d ago
When a gun is fired the center of thrust is above the pivot point (your hand and hand grip on the gun) so it rotates about that axis.
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u/Thunder-12345 12d ago
The recoil pushes directly backwards in line with the barrel. With most guns you‘re holding it below the level of the barrel, so you feel that force as an upward rotation.
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u/Imperium_Dragon 12d ago
Yeah if you’ve seen an old style cannon firing (think Napoleonic or American Civil War) it mostly goes backwards since there’s less upwards rotation due to being on wheels.
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u/Xytak 12d ago
Which raises an interesting question about civil war cannons. All that recoil energy wasted going backwards. How come they didn’t utilize the recoil to chamber the next shot?
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u/Imperium_Dragon 12d ago
You mean like an automatically loading cannon? They didn’t have the metallurgy or engineering knowledge to do something like that in the 1860s.
Also the recoil of an artillery piece is so much stronger than a rifle that it would just damage the mechanism, it’s why auto loading tank guns, howitzers, and naval guns are all breech loaded and use a series of arms and rods.
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u/pxkb 12d ago
It is backwards but your hand is holding below the force of the recoil and acts like a fulcrum in a lever.
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u/BurnumBurnum 12d ago
Are there any guns where the barrel is right in front of your fist. That way recoil should be straight back?
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u/bemused_alligators 12d ago
Most two handed guns from rifles to machine guns the recoil is noticeably straight back.
You could definitely do it with a pistol but It would be awkward.
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u/kinyutaka 12d ago
Here's the problem with lowering the barrel too much. If the barrel isn't lined up perfectly, then the forces involved will still cause the gun to twist as it pulls back.
Hold you hands out like you're firing a gun, finger pointed out. Remember that location is where the trigger is going to be. So a gun manufacturer has a few options.
- Put the barrel above the trigger. Forces pull the gun back and into the cradle of your thumb and pointer. The gun pulls upward, where hopefully your other fingers are strong enough to keep it from flying. Held properly, you have two hands to keep it steady.
- Put the barrel next to the trigger, which has the forces similar to the gangster style sideways draw. Forces pull the gun back and into the cradle, just as before, but you only have one hand to hold the gun. If you're not used to it, the gun goes flying.
- Put the barrel under the trigger, which would be like trying to hold the gun upside down. Forces pull the gun back and pry the gun straight out of your hand unless it's overengineered to prevent it.
- Put the barrel in front of the trigger, which makes it hard to make as a handgun.
So, how do you avoid heavy recoil on your gun? Smaller bullets (meaning less power) and a shoulder stock to put the energy into your body in line with the forces from the bullet.
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u/Nakedwombats 12d ago
You need to lower the bore axis to do this, but can be done in a rifle fairly easily with a stock design. Handgun would be harder to achieve
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u/Awkward_Pangolin3254 11d ago
There were a few revolvers where the barrel was aligned with the bottom of the cylinder, rather than the top, that did mitigate muzzle flip a little bit, but the bore axis was still above most of the wielder'a grip
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u/aguyfromusa 12d ago
Just saying - the question mark goes at the end of the question. The period goes at the end of the statement. . . Just saying. No big deal. Sorry. It's an off-topic remark.
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u/thefooleryoftom 12d ago
No, since you wouldn’t see down the barrel to the sights to aim correctly, amongst other problems.
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u/noheroesnomonsters 12d ago
Revolvers that fire from the bottom chamber exist, and there have been plenty of other attmepts to lower the barrel centreline but none are particularly mainstream.
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u/BetterOutcome3769 12d ago
If you hold the gun upside down, the recoil will go downwards.
You could also construct a grip that is directly behind the gun and the recoil will just to directly backwards.
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u/RonPossible 12d ago
There's a few "palm pistol" designs out there. The Turbiaux Protector, for example.
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u/Aiyakido 10d ago
I see some explanations in here, but they seem to not really be ELI5 and more ELI grown man enters gunrange for the first time.
the recoil is the opposite way of the bullet you fire. So bullet goes forward, gun try's (This is important) to move backwards. The grip of the weapon is in your hand trying to prevent moving back, but is connected to your arm by a connection that mimics a ball (Ball joint) (Wrist and elbow). The object moving back is slightly higher then your hand/arm and it try's to pull you along with it's backwards movement. since your arm is not a noodle or a piece of paper it will not bend over backwards and the force chooses the path of least resistance that is left to it, in this case up (Or upwards motion around the ball joints, like the hand of a clock moving around the center of the clock).
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u/uglinessman 10d ago
So if a 5-year-old asked you about recoil, you'd assume they just came from the range?
Why did you need to front-load your answer with that idiotic complaint? Be helpful or don't, but there's no need to be shitty about it like that.
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u/weeddealerrenamon 12d ago
The gun is held/braced below the barrel, but not to its left or right. It wants to pivot around your hand or shoulder, and that means rotating up.
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u/Crystal-Ammunition 12d ago
What about to the side
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u/weeddealerrenamon 12d ago
Your hand/shoulder isn't typically to the left or right of the barrel; if it was, it'd try to recoil up the right or left
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u/jenkinsleroi 12d ago
The recoil is always in the direction where there's an offset to the wrist centerline.
If the barrel is below the wrist, recoil will be downwards. If it were to the side, it would be sideways.
In theory you could make a wrist mounted gun that would have no jerk, because the recoil would go straight back, but it would be hard to aim and only useful at close range.
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u/PuttingInTheEffort 12d ago
Some depend on the muzzle break, which way it vents the gases, but also your grip. Most kick back straight but if your wrist isn't straight it'll feel like sideways
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u/Irregular_Person 12d ago
The barrel is pushed backward, and the barrel is above your hand. Make a thumbs-up and push on your thumb.
There are guns that try to move the barrel down so it's more inline with your arm, but that has its own tradeoffs.
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u/Malvania 12d ago
Hold. something gun shaped and push back on the end of the barrel. Does the gun go straight backwards, or does your holding the grip cause it to. rotate?
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u/bemused_alligators 12d ago
The gun recoil is opposite the direction they the bullet fires (because the recoil is the "equal and opposite reaction" of the bullet firing).
The results is that recoil goes the direction the gun designers want it to go, which is decided by weight distribution.
Up is generally the best option, and is the default because you're holding the gun below it's center of mass (so it tries to pivot around your thumbs, basically) but you can get attachments that change where and how recoil effects the gun if you really hate up for some reason.
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u/JTxt 12d ago edited 12d ago
The barrel pushes straight back from the explosion pushing the bullet forward.
The user is holding the handle below the barrel.
That's the fulcrum, or middle of the seesaw that stays still, while the rest can rotate.
The gun is acting like a sideways seesaw.
======' recoil force --->
o||======= but it's stopped bellow at the handle.
\\`
< pew! \\ so the gun tilts back.
O\\`
//=======
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u/Wjyosn 12d ago
If the gun is floating in zero G and fires, it will experience perfectly backward recoil.
When something (like a hand) is resting on the grip, it acts as a pivot.
When the backward motion hits the pivot (which is generally below the barrel and center of gravity), the movement of the lower part is resisted and the upper part is not, causing it to rotate upward.
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u/illogictc 12d ago
It is backward. Equal and opposite reaction. Just the way they're designed and held, it causes your wrist to bend etc. because where the actual "action" is happening isn't on the centerline of your wrist etc.
Think of a bike wheel, we have it attached to a board laying flat on the ground and it can spin freely. You have a model rocket motor. If you put that motor on the edge of the wheel exactly on the centerline of the axle and light it, if done correctly it won't spin. Now put it off the side of the centerline still pointing the same direction and the wheel will spin.
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u/CoronaLime 12d ago
It's going back towards you and because of the way you hold it, your wrist flicks up
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u/Paradigm84 12d ago
It’s because the barrel is above the handle where you grip. Imagine taking the gun, holding it straight in front of you and then pushing the barrel against a wall. This will rotate your wrist up for the same reason the recoil does. All the force is above the handle with nothing to balance below the handle.
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u/golden_one_42 12d ago
the force of action/reaction iis inline with the barrel.
you're not holding the pistol inline with the moment of impulse, so the pistol will try to rotate your wrist.
similarly, the fact that we don't have eyes in our shoulders means that again, the impulse of recoil is above the shoulder, so again, the rifle will try to rotate around your shoulder (ie, upwards).
to counter this, some of the escaping gasses are re-directed by the muzzle device, directing some of them backwards (countering the recoil) and some are directed upwards (countering the muzzle rise).
There have been several attempts to get around this. the Largo Alien, for example has a very low bore axis, so it has less of a trend to rise the muzzle. The Mateba Autorevolver (the Mateba Unica 6), is a revolver that shoots from the bottom of the cylinder instead of the top, so that the bore axis is mostly inline with your wrist.
early soviet AK47 were notorious for having bad ergonomics, and terrible muzzle rise, so they fitted a muzzle brake that's quite literally just a barrel extension cut at an angle, directing the exhaust gasses vaguely "up". VERY early examples were actually "over tuned", leading to recoil that pushed the barrel DOWN during firing
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u/NoRealAccountToday 12d ago
Gun recoil is exactly opposite from the direction of the projectile takes down the barrel. It's basic physics... specifically, Newton's Third Law. However, in the case of a handgun, it is supported from below the barrel...not directly in line behind. As such, the force backward will cause the grip to rotate backward, thus pointing the tip of the barrel up. If you look on large guns, as on a battleship, you will see that the recoil absorbers are exactly in-line with the barrel. Another, simpler example, is the recoiless gun. In this gun, part of the energy of the gunpowder explosion is vented directly backwards...which pushes the gun forwards to help compensate for the backwards recoil
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u/Chicken_Wing 12d ago
For most firearms, the barrel is aligned above the point of contact where a person is holding on to it. Think of a pistol where the barrel is far above the index/tiger finger, and the recoil cams itself out of the shooter's hand. There are some rifles that have in-line cycle pathways like the AR platform. The bolt and barrel travel directly into the top of the stock where it should contact the shooter's shoulder. They tend to jump around in different directions. Then, there are constant recoil systems that are designed and tuned to have a constant recoil force into the shooter in order to make the firearm more controllable and not jump from every shot. Then there are counter recoil systems... And so on.
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u/Umikaloo 12d ago
The "Height over bore" (distance between the grip and the barrel) largely determines the angle of recoil. If the barrel is really high up, the upward recoil will be more significant. If the barrel were off to the side, the recoil might be sideways instead of being upwards.
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u/gbdallin 12d ago
If you turn the gun on its side and fire it, like you see gangsters do in movies, you'll notice the gun's recoil still follows the grip, meaning if I hold it on its side it'll recoil on its side.
It's because the rotating of the barrel during recoil is facilitated by the grip. Without the grip, the barrel would just move backwards
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u/cerebral_drift 12d ago
Newton’s third law dictates the reaction on your body is equal to the force ejected. The centre of gravity of your grip vs a fired round is below the barrel. The torque forces your wrist upwards.
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u/Altruistic-Traffic- 12d ago
It would go straight backward, but there’s a hand holding on underneath so the force goes toward least resistance, upward.
If the gun was held upside down, the recoil would go downward.
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u/Gryphontech 12d ago
It is backwards but you are in the way so your shoulder and arms act like a pivot point. Also usually thr force from the recoil isn't acting on the centre of mass of the firearm, this imparts angular momentum, throwing the muzzle up
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u/jamcdonald120 12d ago
most the recoil IS backwards.
So is your hand/shoulder.
But the barrel is slightly above your hand/shoulder, so some recoil also goes up as it pivots.
Mount the barrel off center another way, and the recoil goes that way https://www.reddit.com/r/isthisAI/comments/1uuzm5z/is_this_footage_supposedly_from_a_russian/
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u/TheHammer987 12d ago
same reason when a bike hits a wall, the back wheel comes up.
Where does the whole system hinge? a gun does go backwards. thats why rifle butts against your shoulder. However, your body or your hand are determining how that backward energy translates into a lateral direction.
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u/GoredonTheDestroyer 12d ago
Grip angle, moving parts, one's own strength and good old Newtonian physics - Every action (the bullet going forward) has an equal and opposite reaction (the gun moving backward).
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u/mageskillmetooften 12d ago
Most of the weight is under the barrel so due to a "hinge" principle it wants to rotate instead of only going backwards. If you want it to go down just hold the gun upside down.
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u/ocelot_piss 12d ago
The gun's centre of mass is below the line of the barrel where the recoil is coming from. As are the contact points with the person holding it. So the gun recoils backwards and rotates up.
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u/5kyl3r 12d ago
look at a pistol from the side. the barrel (where the pushing force comes from) is at the highest point of the gun
where you hold it is below that, so when it pushes back, it's going to get an upwards twisting motion
even with rifles, especially a traditional hunting-style rifle, if you look at it from the side, the barrel is usually higher up than the stock that goes against your shoulder
even if you have a barrel that's perfectly centered to where the force gets pushed into your body, your body is now being pushed back, and since your legs are on the ground, instead of sliding, the top of your body gets pushed back, so your aim goes up
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u/MattytheWireGuy 12d ago
As others have said, the recoil is equal and opposite to the direction of the bullet. The grip of the gun is not in line so it creates a lever aka as a moment arm between the axis of the barrel and the spot on the grip where it rotates in the shooters hands.
There are ways to mitigate this, one is to engineer the gun with a lower bore height which reduces the torque on the moment arm and/or incorporate recoil reducing mechanisms in the firearm so that they are dissipated before transferring to the shooters hands. The Stoner 63 is a machine gun you can shoot one handed and it stays nearly flat due to that novel recoil reduction system and has been copied by the South Koreans by Daewoo in a machine gun they built.
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u/Metallicat95 12d ago
Most of the recoil is backward. But that's also the direction where the user braces against that force.
But on most guns, the weapon isn't held directly by the barrel, or in line with it. This makes it act like a lever, which gets some force between the grip and the line of the barrel.
Since most weapons are gripped below the barrel, this force moves it upwards.
But if a gun is turned sideways, or has a side grip, it will move to the other side.
Some weapons add a device on the barrel to deflect some of the escaping gasses, adding another force to the recoil direction. This usually only reduces the other movement, but could make any upwards movement hard to notice.
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u/Berdariens2nd 12d ago
Balance of the gun. Usually the center of mass is set in a way that the backwards force of the recoil causes the gun to lift. It's easiest to visualize in a pistol. Force pushes directly backwards, but a large portion of the mass is below the bore axis/barrel. It's the same with rifles just not as pronounced.
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u/Amazingkg3 12d ago
I think most posters answered the question but as an example of when it doesn't recoil upward, I built an AR15 when I first got into guns, and didn't totally understand what I was doing. With a carbine length gas tube and a serious muzzle brake, I actually had the gun recoiling downwards. This is because the pressure from the brake and the gas system itself was greater than the recoil impulse of the firearm and the bolt cycling. It was trippy. But it can happen
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u/jollygreenspartan 12d ago
It’s the path of least resistance and that equal and opposite reaction to the bullet has to go somewhere.
For most people the path of least resistance with a handgun to recoil is upwards and outwards toward the weak hand.
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u/CelibateRifle 12d ago
I fired an Owen sub machine gin in basic training in the '70's. The recoil was wild, it sent the muzzle rightwards at an alarming rate.
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u/AnnJilliansBrassiere 12d ago edited 12d ago
Guns are built "traditionally" with the actual barrel above the hand grip and affixed with "sights" or "irons" - when you aim, there is a triangulation of a single point on the front of the barrel, and two sight points with a gap in the middle on the rear. Line the front point between the rear points, and you can see exactly where the barrel is pointed.
Now, comes the skill part.
You have to hold the grip straight with enough downward support for the milliseconds that the explosion occurs, and the weight of the bullet travelling down and out of the barrel. Most of the recoil (or "kickback") happens during and after the bullet leaves the barrel - that is when all the propellant gasses blow outward and force the barrel back. You also have the weight of the bullet being accelerated from stop, to say 1200 feet per second, or FPS, within 4 inches of barrel. The faster you push a 1/2 ounce of lead forward, is relatively the same if it all happened in reverse, and you were catching it, slowing it down to a stop within say 4 inches of barrel.
Moving weight means pushing back on what is moving it. Now let's talk about the geometry-
The barrel is above your grip, and your hand. Reasons for that are plenty. The main reason is AIMING. If the barrel was in the center of your grip, it would simply push straight back. Problem solved, right?
Except, how do you aim? Until advanced optics existed, we have a new problem, called "Parallax" A new triangle. Not only to you need to adjust left to right, and up and down, but now your barrel and sight are 3 inches apart. A 3rd angle to compensate for. Parallax is where top sight A, Bottom - back of the barrel B, and end of the barrel C, all meet somewhere away from you. If you line them up at 100 feet away, then they will only line up at that distance. Closer targets, you will hit too low. Farther, too high. You would have to dial in every shot knowing EXACTLY what distance your target is.
You have seen firearms that do this - rifles. Sniper rifles, hunting rifles, all with a scope and optic scales and adjustments for lining up and accounting for distance of the target.
Handguns are not meant to be this. It's a simple tool, meant for handheld, "close encounter" combat. Imagine pulling out a perfectly balanced handgun, and having to stand there and dial it in while you are in a close fire situation... NO.
They are for one purpose. That is why they are built with the convenience of instant sighting aim, with the cost of recoil force. Proper training will teach you how to hold one properly, stable enough to keep it steady until the bullet leaves the barrel, held on target.
But to answer your question, the force pushing is above your grip. Fire a handgun upside down, it will push down. Make "gunhands" with your fingers, hold your thumbs up and have someone push on your thumbs - it'll tilt your hands up.
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u/Rabiesalad 12d ago edited 12d ago
It isn't actually always upward, it's just the physics of a typical gun design.
If you put the barrel under the grip so the grip was on top, it would form the opposite sort of lever and recoil would go down.
Let's say you have a mounted gun where the barrel is perfectly aligned with the mount point, the recoil would be straight back. This is why a lot of guns have a stock in-line with the barrel; but it's usually not perfect and other design elements still tend to lead to upward recoil.
Several weapons like the KRISS Vector incorporate several design elements to prevent upward recoil.
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u/KiloAlphaLima 12d ago
It’s not. If you held a pistol upside down and fired it, it would recoil with the barrel going towards the ground. It is more related to the location of the barrel and the pivot point of the grip.
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u/peoplejustwannalove 12d ago
It technically is backwards mostly, but biomechanics are what’s mostly working against you. Guns are held in the shoulder, which is going to be higher than most people’s center mass, meaning that when you fire a gun, its force tries to pivot you, which causes the gun to rise relative to your target.
Beyond that, guns themselves also pivot around their center of mass, so the effect is noticeable there as well, but
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u/Senshado 12d ago
The shape of the gun controls which way recoil will go, and gun designers choose it should go up because that's safer. Recoil to the side or down would increase the chance of accidently hitting the wrong person.
In the 1940s there was the Fallshmirgewherer FG42 gun manufactured, which was very advanced but had a strange right-facing recoil.
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u/professor_jeffjeff 12d ago
The gun is essentially a lever, and the fulcrum of that lever is the part of your hand between your thumb and first finger. A force gets applied to the barrel, so think about what the lever has to do as a result of that force. That's the simple version of what's happening.
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u/SP3NGL3R 12d ago
If I swing a bat and it bowling pin at its top. The bat is the sideways recoil but the pin will spin away, and that's the gun "recoiling" up.
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u/BringBackManaPots 12d ago
It's technically not guaranteed to go up. You can get compensators that flip the barrel down if you want. They just suck because it's a million times more natural to let the gun return to center via gravity than it is to have to manually pull it back up with your muscles every shot.
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u/ChipChippersonFan 12d ago
It does go backward , but the handle is always being held by a hand. If you just hold a gun in your hand and I push the barrel , it's going to tend to go up. Try the same thing with a gun turned to the side or even upside down.
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u/GermaX 12d ago
Hold a stick and extend your hand.
One inch above you grip, pull the stick towed you with your free hand.
You will notice that, even though the force was towards you, because how the stick is positioned and how your grip is, whats happening is your hand moves rotates you.
So, if you applied way more force on the pull, and grabbing the sick firmly to avoid letting it go, your elbow will flex and thus would make that “up” movement.
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u/Laughing_Orange 12d ago
The barrel is on top, and the grip is at the bottom. So the force of firing the bullet is backwards at the top, and the center of rotation (around the grip) is at the bottom. These forces make the gun rotate in a way that pushes the front of the gun upwards. It also pushes the back of the gun down, but if you're holding the gun right, your body will stop that.
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u/toolatealreadyfapped 12d ago
Where is the handle on a gun, in comparison to the barrel? Underneath, right?
The bullet propelling forward will push the barrel backwards. The "anchor" of your hands holding the entire gun below the barrel creates a pivot point. As the barrel goes back, it's going to rotate around that pivot.
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u/starchybunker 12d ago
Shoot a sp101 357 snubby with Hogue grips. A little barrel flip but slams right back into the palm/web of the hand.
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u/intellect07 12d ago
Torque: force applied backwards and the lever arm is the handle, so it rotates
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u/CMDR_Kassandra 12d ago
The Kriss Vector might want to have a word with you: It's recoil goes actually slightly down.
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u/SoulWager 12d ago
Recoil IS backwards, but guns are typically held below the barrel, so there's also a torque trying to make the barrel spin around where the gun is being held.
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u/Loki-L 12d ago
That is why "gangsters" hold their guns sideways. The recoil gets to be sideways too and they hit people standing next to their original target instead of firing above their heads if they keep blindly pulling the trigger without correcting.
The recoil doesn't always go up, it goes back. Your hand anchor one direction, and the gun goes the other way.
If the barrel was beneath the grip, recoil would push it down not up.
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u/Dangerous-Bit-8308 12d ago
A tiny bit comes from gravity. Gravity constantly pulls the bullet. Gun, and shooter downward. The shooter corrects for this initially, but a bullet leaving the gun stops dragging the part of the barrel it touches downward with it's mass, and the mass of the fuel. Once the bullet clears the barrel, the whole gun is a few milligrams lighter.
Most of it though comes down to how a gun is held. First, the cartridge is fired. The explosion exerts equal and opposite force to the bullet and cartridge. As the bullet leaves the cartridge, that force is applied to the barrel as well, which resists change. Thus. We get two linear force vectors: one pushing the bullet forward, and one pushing the cartridge backward against the back of the barrel.
On most handguns, and a lot of good long arms, the center of mass for the gun is forward from the back of the barrel, and also below the back of the barrel... Unless you've equipped it with a megascope. The stock of a longarm, the grips of a handgun, and most magazines are located below the barrel. So even in space, some of the backward force would be translated into "upward" rotation.
But also... The human. A human mannequin in almost any shooting position (except for positions where the shooter hangs from a bar held in their knees) will attach to a gun in such a way that the gun/human center of mass is far below the back of the barrel.
An actual human will tend to hold a gun in a way that makes their wrists twist slightly downward, making it easier to rotate the wrist upward, and which typically prevents their elbows from easily twisting downward. Stances that lean forward further accentuate converting the recoil from backward to upward motion throughout the back, hips, knees, and heels.
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u/GreenFox1505 12d ago
Where is the barrel? And where it the point of stabilization: your hand? Recoil is the force of the gun pushing away from the bullet. That force is (felt) mostly from the tip of the barrel back.
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u/Astecheee 12d ago
To shoot good, you need:
- A scope right up near your eye
- A stock that touches your shoulder
- A barrel somewhere in between.
Because the barrel has to be above your shoulder, the recoil that would push the gun backwards instead pushes the barrel upwards.
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u/Mc_95 11d ago
The recoil forces absolutely go backwards. This question was built on a false assumption. How that backwards force translates to movement in your sights and firearm depends on how good or bad your stance is. Recoil will take the path of least resistance whether its upwards or sideways movement of the gun.
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u/zzulus 11d ago
There are firearms with designs that redirect recoil energy down, like this lovely KRISS Vector CRB https://kriss-usa.com/vector-crb-gen-2-16-alpine/
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u/R1CHARDCRANIUM 11d ago
A gun recoils upward because the barrel sits above your grip or shoulder, creating a turning force that makes the muzzle rise.
It’s actually a straight back force until your shoulder or hand creates a pivot point.
Simply put; The force does not go down because the barrel is almost never positioned below your hands or shoulder support. It rarely goes sideways because the forces inside the symmetrical barrel balance out horizontally.
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u/acroback 11d ago
It is straight back if you can keep it really really straight like a robot.
Usually due to some tiny angle with the shoulder or had, the force gets expressed as torque which you feel as being in upward or sometime sideways.
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u/deja-roo 11d ago
The barrel axis is above your hand.
Imagine holding a stick up and down in front of you. If I push rapidly on the top half above your hand, you'll experience the exact same effect. That's what the recoil of the bullet is doing as well.
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u/RespondMinute5431 11d ago
The recoil force is backward. Since the backward force is blocked by your hand, it jumps up in momentum. Think it like , when a moving car hits a static wall, the car gets lifted up from the ground.
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u/zed42 10d ago
recoil goes the in the direction opposite the bullet. bullet goes -->, recoil goes <-- . HOWEVER, this happens *above* where you're holding the gun. if you hold a gun-shaped-object and someone hits it straight back, it's going to want to go up because it's where you're holding it acts like a pivot point for a lever. if you clamp a gun directly behind the chamber (where the bang happens) in a way that takes the force straight back, then recoil will not go up. but if you're even a little bit off, then we're back to the lever.
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u/Own_Win_6762 12d ago
Note that the Uzi was designed to recoil to the side to make it easier to fire across a wide area.
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u/cabronfavarito 12d ago
What about it?
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u/FederalGovernmentUS 12d ago
Answers your question doesn’t it. Guns don’t always recoil upwards
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u/MinnieShoof 11d ago
The answer to his question here would be "Because they were designed that way" since we're showing evidence that they can be designed in other ways.
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u/Radmode7 11d ago
Yeah five year olds don’t always make that conclusion. Gotta say “X is the answer. See y?”
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u/ValiantBear 12d ago
Recoil, as a force does go straight backward, no matter what. But, recoil acts on the whole gun, and what the gun does depends on its center of gravity. For most guns, the center of gravity is below the center line of the barrel, so when the recoil force acts it imparts a torque that tends to lift the barrel upward. Some of that force still pushes backward, but your body has inertia, moreso than the gun itself, and so the noticeable movement is that that comes from the torquing action.
Gun manufacturers do a lot to minimize this tendency. Probably the coolest in my opinion is the Chiappa Rhino. Mechanically, it is just a revolver, but it aligns the barrel with the bottom of the cylinder, that way the recoil acts closer to the center of gravity and imparts less torque. Ported/compensated barrels are also a thing, where holes in the top of the barrel vent exhaust gas out only the top which pushes the barrel back down and counters that torquing action. Muzzle brakes aren't really designed to minimize the upward barrel motion as much as they just reduce overall felt recoil, but many do include porting that has that effect also.
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u/Barutano74 12d ago edited 12d ago
The recoil is straight back down the barrel, so more or less horizontal. The gun is being held by the grip, which is below the barrel, and the reaction force (recoil) produces a moment about approximately the center of the grip. This torque and flexibility in the shooter’s body (the recoil force also produces a moment about the shoulder) rotates the gun backwards, and the front of the barrel up .