I've been very happy with my Krieger/Wylde heavy bbl 7.7 twist. I took a recommendation from my brother's success with the same bbl (only shorter) and both of us are shooting sub 1/2 moa center to center! Couldn't be happier!
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I tested with a variety, counting on the higher quality stuff tightening up more than the bulk stuff. The bulk stuff was Lake City 55gr 5.56 and some Wolf Gold, and those were outrageously bad, like 5-6MOA. But there was some Fiocchi 50gr VMAX that is shooting very well from a friend's rifle, and some PMC X-Tac, and both were getting about 2-3MOA at best. I transferred the scope to a known-good Rem700 308 to eliminate the optic as a cause and, predictably, was shooting sub-MOA.The GI or NATO 55gr FMJ ammo is only spec'd for 3 moa. You need to test the barrel with some good commercial bullets, like Sierra 52gr SMK or Hornady 50 or 55gr VMAX. That will usually cut group size in half or less. The bullets make all the difference, especially if you use a scope and it is >9x or >10x power.
I am leaning toward a Bartlein, and spoke with them about chambers and said there should be no problem feeding 556 into their 223 match chamber. I will be going with a rifle-length gas system.I had a Bushmaster chrome lined M-4 that would shoot 3/4 MOA with 55 grain soft points, cannot remember the brand.
The problem with a carbine length AR is the chamber size in some cheaper made barrels. Most are over gassed with the impingement system because of the short gas tube. The cartridge is still up in case expansion when the gun starts to unlock and the chamber has to be Nato or larger for reliability.
Some Barrel people like Green Mt and others have figured out the compromise and tend to be more accurate.
I think If I were all in AR for predator hunting I would go with the full-size rifle and have a barrel chambered for 223 exclusives.
I know there is not much difference in 223 and 556 but we are talking not just chambers but how much throating etc.
The Bartlein I am looking at has a 1:7.7 twist; will there be any issues getting accuracy from 50-55gr v-max ammo from this twist?I've been very happy with my Krieger/Wylde heavy bbl 7.7 twist. I took a recommendation from my brother's success with the same bbl (only shorter) and both of us are shooting sub 1/2 moa center to center! Couldn't be happier!
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That is something I had not considered. The trip is still 5 months out; I may make a last ditch effort to put a few hundred rounds through it and clean thoroughly (I use Dewey exclusively) before opting for a custom barrel.One thing I've also noticed about PSA barrels... They take a bit of shooting to settle down. I've seen many that don't shoot that well, but after shooting them for awhile they settle into nice groups for a factory barrel.
Do some plinking with it with the ball ammo, cleaning it often. Then after you've shot some thru it, clean it again and shoot some ammo of known quality thru it for groups.
My first PSA barrel surprised me with the amount of tiny burrs that came out on the patch after shooting it. Once I had plinked around a bit with it, broke it in some, it settled into nice groups with the first load I tried.
Steven
I've been wondering about this. The Bartlein is only available in 7 and 7.7 twists while the Shilen and Krieger are available in 12. When I spoke with Compass Lake Engineering (Bartlein) they said 7.7 should be fine with 50 and 55gr bullets. But it seems from everything else I've read that 12 would be the way to go.I bought a Kreiger for my Premium build. Once I got the gas block issue fixed it is shooting 3/8th groups. I am just loving it. 12 twist for the lighter 50g bullets.
I'm definitely going to try more break-in before I change barrels. Most of the barrel options I am looking at right now go from 1:7 to 1:7.7 to 1:8 straight to 1:12. Not seeing a lot of options in the middle. I would probably leave this as a dedicated varmint upper, so I am leaning toward 1:12.I have both bolt actions and ARs in 223/5.56 with barrels from 16 inches to 26 inches in length. They are both 1:9 and 1:12 twists, but don't have any in 1:7 (yet). The 1:9's will shoot anything from 40gr to 69gr bullets, typically 0.40MOA for 5 shots at 100yds. I have 1:12s that will shoot 63 and 64gr SPs, but will not stabilize the 69gr SMK, let anything longer/heavier. My longest PD .223 kill has been 481yds (with a 40gr NBT) and a 1:9.
What else do you want to use the AR for after the PD shoot?
Have you done a barrel break-in on your rifle? The classic shoot/clean and repeat process does wonders to break-in a barrel fairly quickly. You might try that also before changing barrels.
At issue is (so-called) over stabilization (from various benchrest periodicals - authors known). Ideally, the bullet axis remains in line with the line of flight*. IIRC, it was an article (or was it a post?) by Walt Berger who said (in response to ideal twist rate question) that the ideal twist rate is that which just stabilizes the bullet. And, apparently so. Otherwise why such variation in twist rates, e.g., twist rate calculators (offered on-line by many bullet manufactures).I've been wondering about this. The Bartlein is only available in 7 and 7.7 twists while the Shilen and Krieger are available in 12. When I spoke with Compass Lake Engineering (Bartlein) they said 7.7 should be fine with 50 and 55gr bullets. But it seems from everything else I've read that 12 would be the way to go.