AR-15 Krieger

[eddism]

I am considering having a AR-15 built using a Krieger Barrel with a 10 twist. The custom fabricator advised that they have never built one with this rifling. They advised that they have built them using the 12 twist for 55gr frag loads. Its my interest for carbine target competition and think 10 twist would make for flatter trajectory and longer distance with heavier loads. The rifle builder says this riflebarrel is usually 6 to 7 twist.

Any advise is appreciated.

TY

 

[atblis]

It depends on what bullet you want to shoot. The bullet manufacturers will generally tell you what rifling is good for their bullets.
1 in 7" and 1 in 9" are the two common AR Twists. 1 in 9" does well up to about 69 gr bullets. 1 in 7" is need for the heavier bullets.

Here's Krieger's info.
http://www.kriegerbarrels.com/DCM__AR_15-c1246-wp3394.htm

I'd go with a 1 in 9" as there are some good 69 gr bullets and it'll still do well with lighter bullets.

 

[Kurt_D]

1:8 for anything from 55gr to 77gr in an AR15. That's what I'm going to use in.

Twist won't effect trajectory enough to worry and "longer distances" usually means match bullets in the 69-77gr range, 1:10 would be marginal with 69gr and useless for 75 and 77gr bullets.

 

[Slamfire]

I don't have much experience shooting bullets lighter than 69 grains in the .223.

A 1:9 twist will shoot 68's, 69's, but will not necessarily shoot anything heavier with any sort of accuracy. I have seen 1:9 twist barrels absolutely blow chunks with 75 grain bullets.

My barrels are 1:8, but then times have changed. My 1:8 barrel will shoot 68's, 69's, 75's, 77's, and 80's with outstanding accuracy to 600 yards.

I believe tighter twists, such as 1:6 or 1:7 are for 90 grain bullets. I don't know as I am not shooting those

 

[Maverick223]

I would barrel it with a 1:7 for long range use and 1:8-9 for general purpose rifles, but if you are really serious and want to use the heaviest projectiles at longest small caliber ranges (1000yds or so) 1 in 6.5" would be the best. Krieger makes a great barrel and is my personal favorite FWIW.

 

[browningguy]

I'm surprised Krieger even offers a 10 twist .223 barrel, i've never heard of anyone using one before. Go with an 8 or 9 twist as mentioned above and you'll be fine.

 

[Kurt_D]

1:8 is still the best choice for anything that's going to fit in a Ar15 mag, 55gr-77gr. One of the guys that does the ammo test on ar15.com uses a 1:8 twist and his "control" is hand loaded 55gr rounds. If you're going to load one at a time 1:8 will handle the 80gr SMK too.

 

[eddism]

Looks like I need to crunch some numbers and consider the feasibility of this.
Thanks...

 

[MCMXI]

Krieger makes a great barrel and is my personal favorite FWIW.

I've got a couple of Krieger barrels and they are top quality without a doubt. The quality is evident when you shoot AND when you clean. Passing a patch through a barrel with a polished 16 micron finish is a joy and say goodbye to any kind of copper fouling. My .308 barrel now has 559 rounds through it. I didn't have to remove any copper after the 5th round!! To clean, I pass a couple of oiled patches through to remove the carbon followed by a few passes with a nylon brush. Finally a few more oiled patches before the rifle goes in the safe and a dry patch before firing.

As for the twist rate for an AR, both my .223 AR barrels have a 1:8 twist and they work very well with anything from 55gr to 80gr. I typically shoot 77gr SMKs out of the 24" barrel and 75gr Hornady bullets out of the 16" barrel with very good results.

 

[eddism]

TY 1858, great advise for sure. I own a T.R. built M852 and havn't had the joy to begin its break-in. This is my first Krieger .308 and want to get it right the first time. Its target data reveals the .5" tolerance via D. Rooney. He said it is perfect. Yah, I asked D to draw me up an AR-15 with the 10 twist. The above is his response. I checked Krieger and indeed 10 twist isn't one they have on the shelve.

With regard to the break-in of the M852. What bore-cleaner would you advise? Diamond? I've got Remington 40-X on hand. Would this serve the purpose of removal of copper, etal. Or should I consider another?

Also, I have aquired a spank'en brand-new Cimarron Model 9 Evil Roy. Would nitro-solvent damage its bluing? I heard never use nitro on a blued finish. Is that the matter of fact?

And finally, I got a new FNH SPL9 Rifled Shotgun. Should this one be broke-in the same manner with regard to copper-fowling if I decide to use jacketed sabot-slugs?

Looking forward to getting busy!

Thanks,

 

[Zak Smith]

[Its my interest for carbine target competition and think 10 twist would make for flatter trajectory and longer distance with heavier loads.

No go, and this doesn't make sense. As others have said, heavier (it's actually "longer") bullets need faster twist, not slower twist. 1:9 is standard twist for 55-69 gr loads. Some people have luck with 75-77 gr bullets with 1:9, but 1:8 is the proper twist for 75-77gr bullets. I have a 1:7.7 barrel that shoots great too.

With regard to "carbine target competition"-- it's generally a good idea to look at what the top national competitors are using; if none of them are using what you're proposing, it' probably a bad idea, unless you're one of them already and are doing something new for a particular purpose. It doesn't sound like this is the case.

If "carbine target competition" means something like 3-Gun or action rifle, then just stick with a 1:9 or 1:8 barrel.

-z

 

[eddism]

I got the reply from Krieger Barrels regarding this barrel today. They will custom ream a 10 twist barrel in a .223. Because it is custom, there would be a long wait. Also, additional charges will be added because it is a special request and will be collected upfront. They warned that there is also the problem of timing and the gas port in the rifle groove. So, for all the little difference that this unique barrel might bring. Little will change as far as the performance of factory ammunition. They also added, that they have fabricated 10 twist for the .233 barrel. But, those customers where pro's and hand made their bullets out of billets of brass. Also, that 1-9 twist is more than sufficient for ballastic stabilization of any standard .223 bullet. So, looks like its going to be 9 twist in this rifle for me.