Barrel Twist?
I am building a ar varmint rifle with a 20" or 24" barrel. What rifling twist should I use? My range will be about 200-300 yards. I will most likely use a heavier grain than the 55gr. Any suggestions?
Originally Posted By scrufy18:
I am building a ar varmint rifle with a 20" or 24" barrel. What rifling twist should I use? My range will be about 200-300 yards. I will most likely use a heavier grain than the 55gr. Any suggestions?
1/8 is a good all around twist rate, or you can go 1/7.
8 twist for sure.
Originally Posted By scrufy18:
I am building a ar varmint rifle with a 20" or 24" barrel. What rifling twist should I use? My range will be about 200-300 yards. I will most likely use a heavier grain than the 55gr. Any suggestions?
Most of the quality AR stainless steel precision barrels in .223/5.56 will be 8 twist which is a good all-around rate.
For varmints, you'll be typically using the lighter bullets and the original twist of 1/12 isnt a bad call. However....
since you are using an AR15 you'll be thinking of heavier bullets as well. I think the 1/9 is the way to go. Some will cringe but I get very good results will all bullet weights from 50gr to 68 grain. I have not fired any bullet weights outside of those so I am not able to comment. Also, keep in mind that some people will say that the lighter jacketed and more frangible bullets can not handle the higher twist. I've used the Speer 50gr TNT will good success out of my 1/9 twist AR15, and I'm not %100 sold on the tight twist being a factor in shredding bullets, I think it is more so velocity related.
Either way..... the 1/9 is a catch all and it does it all very well. Out of an AR15, that is the twist to go with, IMO. The 1/8 or 1/7.5 twists will do better with the heavier bullets or so goes the theory, but again the lighter bullet more typically used for varmints may not like the high twist as well. YMMV.
Originally Posted By JRBL1A1:
For varmints, you'll be typically using the lighter bullets and the original twist of 1/12 isnt a bad call. However....
since you are using an AR15 you'll be thinking of heavier bullets as well. I think the 1/9 is the way to go. Some will cringe but I get very good results will all bullet weights from 50gr to 68 grain. I have not fired any bullet weights outside of those so I am not able to comment. Also, keep in mind that some people will say that the lighter jacketed and more frangible bullets can not handle the higher twist. I've used the Speer 50gr TNT will good success out of my 1/9 twist AR15, and I'm not %100 sold on the tight twist being a factor in shredding bullets, I think it is more so velocity related.
Either way..... the 1/9 is a catch all and it does it all very well. Out of an AR15, that is the twist to go with, IMO. The 1/8 or 1/7.5 twists will do better with the heavier bullets or so goes the theory, but again the lighter bullet more typically used for varmints may not like the high twist as well. YMMV.
So you are saying that the lighter the bullet the less twist that you need?
Originally Posted By scrufy18:
Originally Posted By JRBL1A1:
For varmints, you'll be typically using the lighter bullets and the original twist of 1/12 isnt a bad call. However....
since you are using an AR15 you'll be thinking of heavier bullets as well. I think the 1/9 is the way to go. Some will cringe but I get very good results will all bullet weights from 50gr to 68 grain. I have not fired any bullet weights outside of those so I am not able to comment. Also, keep in mind that some people will say that the lighter jacketed and more frangible bullets can not handle the higher twist. I've used the Speer 50gr TNT will good success out of my 1/9 twist AR15, and I'm not %100 sold on the tight twist being a factor in shredding bullets, I think it is more so velocity related.
Either way..... the 1/9 is a catch all and it does it all very well. Out of an AR15, that is the twist to go with, IMO. The 1/8 or 1/7.5 twists will do better with the heavier bullets or so goes the theory, but again the lighter bullet more typically used for varmints may not like the high twist as well. YMMV.
So you are saying that the lighter the bullet the less twist that you need?
Yes. If the bullet weight is below 55gn it will be happiest with a 1/12 - that is 1 revolution in 12". If you are using a heavier round 62gn or higher it will be happiest with 1/7 - 1 revolution in 7". If you are going to shoot primarily 55 - 62 grain bullets 1/8 would be the ticket. If 55 gn is all you ever want then stay with the 1/9.
I have a 24" 1/9 barrel on my varmint AR. It is very accurate with 55gr bullets.
1:12 Twist 42-55 grain range
1:9 Twist 55-72 grain range
1:8 Twist 55-79 grain range
1:7 Twist 62-77 grain range
>>>LINK TO FULL ARTICLE ON TWIST RATES<<<
I am just about finished building a Target AR-15 using a 26" 1:7.7 Krieger Barrel.
