questions on twist rates...

[tiggere]

new to the forum but I know you guys will be able to give me the best answer...this will not be for a bolt gun...rather an Encore pistol barrel in 6.5 Grendel...now the question is...

I will be shooting 123 SMK's and 129 SST's,some 120 Ballistic tips till I run out)...the standard twist rate that I have seen is 1 in 8...how does that figure relate to barrel length and velocity...I am wanting a 13" to 15" barrel...so with one that short running the 123 SMK's around 2300 fps would you still choose the 1 in 8 twist...will I be able to get by with a 1 in 9,shilen's recommendation by the way per their website)due tothe lower velocity...

Ok...now your wondering why not a rifle barrel...I have the 6.5 Grendel in an 24" AR15 so it will have to do for now...

Thanks in advance...

 

[JDJones]

I would stick to the 1-8 twist as I feel you can't over spin a bullet,till you get crazy with the speeds and pressure) but you can underspin one and your accuracy will suffer. The differance in velocity between the 1-8 from the 1-9 will ne completely insignificant it'll very more for barrel to barrel with the same twist rate.

Again in my oppinion its better to error on the side of caution and go with a faster twist than a slower, some guys try to ride a thin line here and somtimes get burned, i've seen it happn with hot 22 cals, guys want the slowest twist that they can get away with trying to get a bit more speed or try to reduce the RPMs to keep bullets from blowing up and end up with a gun that won't shoot the heavier bullets like they wanted.

 

[3sixbits]

If you are going to pop for a custom barrel blank for a 6.5 Grendel build, the best choice would be a 1 in 8 3/4" twist.

This recommendation comes from Bill Alexander to me.

Note: You will have to go to a cut rifle barrel to get that twist. Nobody I know that does button barrels does that twist.

Not going to spend the bucks for a top end barrel blank, then I would vote for the 1 in 9 twist.