260 AR 10 Build

[Herzo]

Educate me a little here. Is there a rule that limits the bbl length on an AR Tac rifle to 22 inches?

The NRA & CMP have finally settled on 22" barrels and 16 power scopes, until they change their minds (again).

CMP weight limit 14#, NRA weight limit 15# with all accoutrements including bipod, scope, sling and magazine.

 

[bks22345]

Shooting a 140 grain Barnes Match Burner. Approaching 1/2 MOA this morning {1.2" @ 200 yards} with 0.020" off the lands. Was hoping for a little better. I may try their 145 grain MB, it's BC is substantially better and I should be able to maintain the same velocity that worked with the 140. I tried a Hornady 123 ELD-M, the results weren't encouraging plus it will fail to make 1000.

NRA rules do not allow an adjustable gas block, but the ejection pattern was close enough that I may not need to make the change.

The rifle seems to be cycling comfortably, it could be the rifle length buffer is softening it up. Recoil is only slightly more than my 6.5 Grendel. That the rifle is in at just under 12 pounds is probably helping. I’ll probably add another pound or so before I'm finished.

I think the 140 and 145 MBs are a hit or miss. I’ve had much better luck and consistency with the 140/142 SMKs.

 

[ebb]

I have zero knowledge on AR Tac rules. The OP mentioned that an adjustable gas block was not allowed, that is the only rule I know, and learned it here. I have a friend that built 2 AR 10s with 26 inch barrels and the smith recommended moving the gas block almost to the end of the barrel. He loved it that way, smother operation and almost bolt action speed.