So my .300 upper arrived with a 1:8 twist instead of 1:7

[J]

I'd stick with the 1:8. I have a 1:7 that I can only shoot subsonics out of (its suppressed with the can buried under the handguard). It keyholes like crazy with supersonics, and I stopped after one mag when I very luckily didn't get a baffle strike.

I have a 1:8 that shoots 147s, 208s and 220s great.

YMMV

[brutal]

I'd stick with the 1:8. I have a 1:7 that I can only shoot subsonics out of (its suppressed with the can buried under the handguard). It keyholes like crazy with supersonics, and I stopped after one mag when I very luckily didn't get a baffle strike.

I have a 1:8 that shoots 147s, 208s and 220s great.

YMMV

Good to know.

However, what length barrel?

My AAC branded 9" is 1:7, no issues, no keyholing subs or supers (that I recall.) However, I really only shoot subs out of it now, and mostly my own loads unless I let someone else run it, then factory REM subs.

[J]

Good to know.

However, what length barrel?

My AAC branded 9" is 1:7, no issues, no keyholing subs or supers (that I recall.) However, I really only shoot subs out of it now, and mostly my own loads unless I let someone else run it, then factory REM subs.

8" polygonal rifled.

I'll check my supers. They might be lighter, but think they are 147s. I don't really shoot them any more.

I think I soiled my pants a little when I walked up and saw the target after shooting 10 through the gun and can. Jhood was there... You couldn't have asked for a more perfect sideways profile hole of the projectile through the paper. At 25 yards. Can't believe I didn't trash the can on that. Lesson learned the easy way this time.

It's very possible it's just this type/lot of supers I got, and would be fine with other supers.

Since it's buried under the handguard, I can't really test other supers in it, or the brake will blast off the finish of the inside of the handguard with no can. If I had a stronger desire, I'd swap the handguard for some unsuppressed testing and then swap back.

[Rucker61]

8" polygonal rifled.

I'll check my supers. They might be lighter, but think they are 147s. I don't really shoot them any more.

I think I soiled my pants a little when I walked up and saw the target after shooting 10 through the gun and can. Jhood was there... You couldn't have asked for a more perfect sideways profile hole of the projectile through the paper. At 25 yards. Can't believe I didn't trash the can on that. Lesson learned the easy way this time.

It's very possible it's just this type/lot of supers I got, and would be fine with other supers.

Since it's buried under the handguard, I can't really test other supers in it, or the brake will blast off the finish of the inside of the handguard with no can. If I had a stronger desire, I'd swap the handguard for some unsuppressed testing and then swap back.

May do more than blast the finish: