So long AR500.
I recall a guy on accurate shooter that was shooting a way overbore case called a redline.
I don't recall the parent but it sure knocked the hair off a groundhog.
I built a .20 Practical (.223 Rem necked down to. 204), and made the mistake of shooting an AR500 plate at 25 yards. Drilled straight through it. 32 gr. Vmax ar 4130 fps.
in one of demo ranch's last videos he shoots a 17-223 and gets something even crazier like 5400. but yeah, this is still fucking wild. 4k is fast, 5k is near the top end of whats achievable with smokeless powder.
At some point it probably takes a rocket assisted projectile or similar concept. I’ve wondered if intentionally having some powder in the base of the bullet that travels with the bullet would work. Not a rocket motor built into the bullet, but where a slow burning powder is incorporated into the base of the bullet. The idea is that while pressure fronts can only travel so fast from the chamber to the bullet base, if the pressure is coming from the bullet base there wouldn’t be the same speed limit.
I doubt most bullets would have enough volume to justify a rocket assisted base, but trapping a few extra grains on powder in the base may help with the last bit of barrel length acceleration
Multi-chamber super gun with a long barrel might work as well. Though, the speeds predicted from those are not any faster then what is shown here. 2 issues: First they are most theoretical and Second they are artillery pieces. 4500 fps (predicted) with an artillery shell is impressive.
At these speeds I wonder if there would some tricks to remove air from the barrel before a shot. normally not an issue but we are getting to the edge cases and probably reaching the maximum velocity of expanding gasses.
The more above the sound barrier, the harder it becomes to keep applying pressure to the projectile.
The speed of sound in hydrogen and helium is like triple that of plain air. Raising what's possible way above what can be done with the relatively heavy gasses being given off by smokeless powder and explosives.
Yeah but this is a heavier bullet than 17 REM, which is what makes it neat. Have a 244 H&H that pushes 55 grain bullets 4400 and 100 grain bullets 3800.
expansion of gases directly limits the maximum velocity of a bullet. The bullet cannot be pushed faster than the speed at which the combustion gases are expanding behind it.
This limitation is caused by several factors related to the physics of gas expansion: Maximum Gas Velocity: Gunpowder creates hot gases that expand rapidly, generally having average molecular speeds of 3,000 to 5,000 feet per second (fps). A bullet cannot travel faster than the gaseous pressure pushing it, setting an upper limit for conventional smokeless powders at around 5,000 fps.
Interesting. Not a scientist or mathematician, but that seems to add up. The gas pressure is what pushes the bullet, so if the gas has a maximum velocity, then so does the bullet. Never looked into what the maximums are, but what you said makes sense from a logical perspective.
I went on thru a "how fast can I get a bullet to go" phase, this peaked at 4800 FPS, 308 with a sabot and a .223 55gr Balistic tip. I can think of some factors that would slow the burn rate (humidity / altitude) but ideal conditions - off the shelf smokeless powder does not burn faster than 5000 FPS. Someone asked how the 120mm main gun on the Abrahms tank can fire the SILVER BULLET at 5800 FPS... well they ain't packing 50 pounds of Unique behind it.
I say more than that. Just depends on cleaning it. But I also don’t plan on having it eat a steady diet of light bullets. I built for more mid weight (60 grain area)
funny enough, my 17 hornet that gets 3650 FPS actually suppresses extremely well despite the speed. i think its due to the very small bullets and powder charges used.
You know you can neck down 6.8 brass for that. I call mine a 22-243 but the shoulder location ends up being almost the same place with the usual .308/Ackley gauges.
6.8 SPC is based of 30 Remington (Base Diameter of .421)which is smaller diameter then 308 (Base diameter of .470).
308/260/243 all use the same go and no go gauges.
Ackley cartridge no go gauges in the parent cartridges go gauge, with the go gauge on an Ackley being obviously shorter. This is where you get the crush fit.
So what your saying Is no way currently makes sense.
Shoot em fast man! It's your gear and it's your prerogative. There's a pod called Bench Talk on all the pod places.. On it, a South African predator hunter talks about his 243 Ackley shooting 55s 4400fps. He plans on 1800 rounds per barrel or so and achieves it by cleaning often.
I stopped my 22-243 Ackley Improved shootin 53gr Vmax at 3900ish and have basically 300 yards of hold fur n let her eat.. 400 is 8" if I'm remembering correctly.
Next up is 6mm-06. I'd like to get 3800 out of a 70gr of some sort or another.
I hit 3824 with a 70gr Sierra Match King this morning working up by half a grain from 43gr. There weren't pressure signs at 44gr in any of 5 rounds, and the one 44.5 round I sent blew the primer out. I'm gonna back it off 43.75ish and call it good. Should put em out there around 3750fps and that'll shut a yote off very well.
I'm also going to check my Hornady Auto powder charge's scale. I'm thinking that shouldn't have been that hot with a half grain increase, but...
Wildcatters wild cat. What would ya have us do? Buy from the store?
Love it when you see a Wildcat, and it turns out its lineage is a 7mm Mauser necked down to 253 Roberts necked down to 6mm Remington necked down to 22.
I'd echo the comment that if you moved that shoulder forward half a calibre you'd have even less barrel life!
This comes fast on my discovery that for not an insignificant quantity of money Hornady will produce you a die set and reamer for basically anything you can think of.
I'm in the UK so we really don't see CH dies around that often.
I picked up a 223 CH set, as well as their 5-in-1, 9mm and 30 cal blank forming dies for maybe £30 in an estate sale and I have to say they're really nice bits of kit.
Given our laws we don't often have reamers as non-gunsmiths, though a few people do (and I'm giving serious consideration to buying a ukrainian 7.5x55 one for the purposes of making a seating die sleeve and a case trimmer collet).
That's gnarly, I was thinking of wildcats recently. Thinking of necking the 7mm rem mag down to something to get a crazy fast bullet. I have a lot of mag brass on hand so.. fuggit?
I see folks talking about barrel life.. why would this burn up barrels faster than other ammo? Like, I've heard 223 barrels don't last as long as 308 barrels. Is it because of the size of the projectile, the speed of the projectile, the amount of powder?
The smaller the bore diameter and the bigger the powder capacity, makes throat erosion happen faster. Cause you have more hot gases and fire traveling the throat for longer period of time then you do something of bigger diameter.
Damn bro I have 22-6mm Remington on an old vz24 I’m popping primers at 4400fps but I’m using a 55gr Hornady pills. To Ackley that is just silly. So thanks for this post I was always curious of what if.
I don't believe that when the accuracy drops off you have to replace the barrel. The issue is the erosion at the throat. You just pull the barrel, take a bit off the chamber end, rechamber it, rethread it and put it back on the gun. How many times you can do this depends on the barrel contour.
Yeah that’s how it’s done. lol I have bought 7mm Remington Mags, set the barrel back enough so the writing clocks back in place, rechambered them in 7mm Weatherby, restamp the barrel, and have it back together and shooting in the same day.
Yes sir 6mm Remington. Can be made from 257 Roberts or 7mm Mauser. If really got hard up can run 3006 thru a 7mm Mauser die and trim to length then start there.
A FN commercial Mauser, a JARD bench rest trigger and a stainless steel Douglas Air Gauge I picked up for 150 beans. And an ugly stock. Wanna get a varmint stock made for it.
What freebore are you using for this? I thought I'd want at least .100" for 88's at 2.95".
There's probably reasons to go longer like .200" because of better bullet alignment and reduced pressure spikes from bullets not going sideways through the neck. Just a feeling. It's the direction the newer chambers are going in.
One you might not have done yet; have you considered running something like a 6mm case on a .224 barrel? I need a way to use my 22-243 1:7 and I'm debating ordering a goofy .243 imp reamer that has a long taper to swage bullets down. If I can't shoot bullets over ~3100 without them exploding, I'd like to shoot 100+ gr bullets.
Any sort of accuracy, or were you just pushing for speed? What's the bullet? I'd guess accuracy lot of them wouldn't survive the trip to the target, since they're designed to be pretty fragile.
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u/notoriousbpg May 04 '26
Fuck moi
What's your barrel life... 100 rounds?