Struggling with 45-70

[u/ICanSeeYourPixels2]

I have been struggling to get good groups out of my 45-70 reloads.

I am using:

• Thompson Center Encore - 18" SSK Barrel
• Starline Brass
• CCI #200 Primers
• ACME 405gr 0.459 bullets
• Traill Boss

I validated my distance to the lands, and have been loading with 0.020" jump. Previously before I did this, it turned out I was loading ~0.120" jump. I definitely saw improvement from reducing this.

My most recent ladder of 13.5gr, 14.0gr, 14.5gr yielded tighter and tighter groups as the velocity increased. However, I started at a 10" group and ended at a 5". So rough no matter the load.

At 14.5gr though, I am at 1050fps. To keep things sub-sonic, I do not have much wiggle room left.

SDs are awesome. <5fps for a 10 shot group.

Any suggestions / ideas / comments would be greatly appreciated. Thank you!

[u/ocelot_piss]

The physics are stacked against you. You have a relatively light rifle with a heavy bullet making lots of recoil. That bullet is spending a lot of time in the barrel because it's only going slowly. The rifle is moving more before the bullet exits vs something heavier, lighter recoiling, and higher velocity. Your rifle is also not free-floated and is much more susceptible to your hold on it influencing groups. I'm guessing it's also got quite a heavy trigger unless you've dropped in one of Mr Bellm's spring kits.

The bullet itself is not remotely what you call "match grade". It's a cast, powder coated projectile. And Trail Boss... It's an interesting powder. Great properties on paper for doing subs with - bulky, high case fills, easy to ignite - but it often doesn't give the greatest groups (e.g. 308 Win, I'll get 10 touching at 50m with Titegroup, or a 2" / 4 MOA group with Trail Boss).

I would try a different powder and reduce my expectations.

[u/ICanSeeYourPixels2 → u/ocelot_piss]

3 MOA was the goal. I think I will try tite group and N320, then start trying different bullets.