Twist rates / groups

**Baffled** · July 17th, 2010, 11:52 PM

Baffled once again, need some thoughts on the twist rate of a 1:9 on the AR-15, I have a 1 to 1.5 inch group at 100 yds. have used several loads with the XBR-8208 powder, 25.0gr with 52 gr hornady A-max, and 55 gr V-max with COL at 2.26 in. with 20 inch nation match barrel. I believe I should be able to do much better at bench rest than this, any thoughts? going to try to reduce the speed from 2800 fps to about 2100 and try some 62 gr solid copper, I am looking to put them on top of each other at 100 yds in 5 shot groups. Any info would be greatly appreciated.

**Baffled** · July 18th, 2010, 12:56 AM

Twist rate on 223 Rem. hunting rifle is generaly 1:12 and they shoot tight groups, anyone have any great load data or info on the topic on the 1:9 twist in the AR-15 area? I would like to be able to reach out to 400 or 500 yards with great results and be able to be under 1 inch at 100 yards bench rest shooting..

**Lycanthrope** · July 18th, 2010, 10:09 AM

In my experience, 55gr flat based bullets shoot well out of a 1:9, but when you have longer boat-tails like the Hornady you need to step up the weight. 62gr+.

69gr Sierra Match King over Varget works well in my 1:9's loaded to magazine length.

Lycanmovedyourthreadtoriflesthrope

**knight0334** · July 18th, 2010, 11:15 AM

Solid copper bullets will be longer than lead bullets of the same weight, which means you will will likely need a faster twist rate. Also, if you lower the velocity, you will compound that need for a faster twist rate too.

.224" lead bullets from 50-62gr and some 69gr perform well in 1:9. If you go to 69gr copper slugs, and lower the velocity - you will need a faster twist.

**unclesam099** · July 18th, 2010, 12:26 PM

To echo what the others have said, try a heavier projectile. Varget is a good powder to use for those heavier projectiles. Sierra Match King or Hornady 69gr should suit your needs with that twist rate.

**aubie515** · July 18th, 2010, 12:38 PM

I would try different powders...especially Varget. I only use Hornady bullets and know that their 55gr Vmax work well in my .223 rifles.

**Baffled** · July 19th, 2010, 04:14 PM

Ty all for your thoghts and support, I have a better understanding now on this and will try a few more things before spending a fortune on a new barrel.

**Tim Ault** · July 19th, 2010, 06:12 PM

Originally Posted by Baffled

Ty all for your thoghts and support, I have a better understanding now on this and will try a few more things before spending a fortune on a new barrel.

Good idea. try some flat base bullets too. BTW what make is the barrel/rifle and i assume your shooting with a scope? Dont blame the barrel till you have ruled out all the other variables Also 1 moa is still very good for an AR ,some can do better some cant.Just food for thought.

**bgeddes** · July 19th, 2010, 08:20 PM

My Benchrest AR is a 1:8 twist barrel. It shoots 69gn Sierra Matchkings with 24.8gn of Reloader 15 very well. A 1" group at 100 yards is not a problem, if I do my part.

My upper is a 26" White Oak.