AR15 barrel twist

Tikka280ai · Jul 24, 2015

What twist rate would be best for 62 grain barnes ttsx and 55 grain v max. Looking at building a new upper but dont know what twist rate to go with

Enslow · Jul 24, 2015

1:8 twist for copper. The 55 grain vmax is fine with the faster twist also.

Lycanthrope · Jul 24, 2015

Barnes are longer than traditional bullets, so youd want something that will stabilize a standard 70-75gr lead bullet. Curious, why are you going with the 62gr TSX? You would probably get better performance with the 55s.

Tikka280ai · Jul 24, 2015

I was thinking that the barnes would stabilize better and be more accurate at longer ranges. The AR setup I have now wont group 55 grain vmax with I think 25.5 grains of varget into a golf ball at 100 yards. myself my dad and uncle all struggle to group tight with my current set up. I was going to try an 18 or 20 inch medium contour barrel with a free float handgaurd and hope I can work up a better load for it

Lycanthrope · Jul 24, 2015

Problem with barnes is, the lower the velocity, the less expansion you will get from them. Copper is hard and really needs some good energy to open it up. Ive seen some tests that show that the TTSX actually doesnt expand as well as the TSX, but it will give you a slightly better BC. I havent run velocity/drop charts recently, but you wanna keep it above 2k fps and even that can be marginal at times. Ive shot deer with my 223 using 53gr TSX and it did just fine. I tried some heavier bullets I was gifted by bobcat, I think they were 70s and they stabilized, but didnt group for crap for me.

Norske · Jul 24, 2015

You could call the gun maker's customer service. I'll just guess something faster than 1 in 9.

Kentucky Windage · Jul 25, 2015

I can't seem to find a load that my 223's hate with good ol IMR 3031. I have had excellent results with 50, 53, 55 V-maxes and 52 A-maxes.

jr2280 · Jul 25, 2015

1:8 should serve you well.

Norske · Jul 25, 2015

Enough guessing. Search for barrel twist calculator and you will find a bunch of links. The Ken Howell article is interesting. Berger bullets has a calculation page. Browse the various links.
Note the twist rate is determined by bullet LENGTH not weight.

PrairieGhost · Jul 25, 2015

Bullet length/ballistic coefficient, I agree with you Norske. The old 30 call 220 will stabilize easily, while some struggle with the 210 Berger. Often they can stabilize the 208 Amax, but not the Berger. Evidently the Amax has a larger void up front that also affects the stability world.

Petras · Jul 25, 2015

my 20" 1:7 twist YHM barrel shoots 55g v-maxes just fine. approximately .75" groups if i remember right. It really loves the 77 sierra match kings with .47" groups at 100 yards. that being said, anything 1:9 or faster should handle those boolits well.

Tikka280ai · Jul 26, 2015

Thanks for the info. Ended up ordering a 24 inch stainless heavy barrel from some in a 1 in 9 twist. Hoping it will work better than my other one

AR15 barrel twist

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