Twist rates? Confused...

[DarkRose]

I'm getting ready to start on an AR project, and am a little confused by the twist rates I see...
It'll probably be more of a varmit/target gun, so I'm going to assume right now I'll probably be loading or buying 55 gr. or 60 gr. bullets.
I'm seeing 1:8", 1:9", and 1:14" twist rates... I read a couple places that 1:12" is ideal for 55 gr., but don't see 1:12" anywhere I've looked so far...

What would probably be my best compromise?

If I start getting into longer ranges (I'd like to start working up to 400+ if I can find a range long enough) are the 55/60 gr. bullets heavy enough at that distance?

 

[Duce]

The trend right now, to get the most out of an AR at distance is done using bullets as heavy as 70 grs. This requires a fast twist barrel, up to 1"in 7". Hope this helps........Duce<><

 

[SemperFiUSMC]

I'm getting ready to start on an AR project, and am a little confused by the twist rates I see...
It'll probably be more of a varmit/target gun, so I'm going to assume right now I'll probably be loading or buying 55 gr. or 60 gr. bullets.
I'm seeing 1:8", 1:9", and 1:14" twist rates... I read a couple places that 1:12" is ideal for 55 gr., but don't see 1:12" anywhere I've looked so far...

What would probably be my best compromise?

If I start getting into longer ranges (I'd like to start working up to 400+ if I can find a range long enough) are the 55/60 gr. bullets heavy enough at that distance?

55 gr can be stabilized anywhere from 1:12 - 1:8 twist. a 1:10 or 1:9 are best for that round. 62gr steel core can be fired from the same barrels. I fire 62gr steel core from my 1:9 twist 16" carbine.

60 gr lead core can be stabilized anywhere from 1:10 - 1:7 twist. A 1:9 - 1:7 are best for that round.

70+ gr require a 1:7 twist. I fire 60 - 90gr rounds from my 24" BB 1:7.

You can get man sized hits all day long at 500 yards with a 55gr round. Used to do it in the Corps all the time. If you want to get sub-MOA shots at that distance or longer, you'll need a heavier round and a faster twist rate.

 

[DarkRose]

Ok, I was thinking more of coyote size targets out to 500 yards... So I'd probably want a heavier bullet with more of a 1 in 8" twist?

Looking at a 24" bull barrel free float handguard setup, flattop, scoped.

 

[AccuRat]

Yep. My CZ 527 Kevlar has a 1:9 twist which is fantastic for prairie dogs using 40-55g bullets. I tried some Federal Gold Medal Match 69g fodder just to see how it would shoot, and it didn't shoot nearly as well as it should have, being world-class ammunition. Obviously the barrel twist rate because moments before and after shooting the 69g, I was putting Black Hills Blue Box 50g Vmax in to 1/2 to 3/4 inch without giving it much thought. For my purposes, the 40-60g bullets are more than enough for 500 yard shots on varmints and the 1:9 twist is perfect in that realm.

 

[RichardR]

All of my AR's are 1:9 twist, but then again I only shoot 55-62gr through them, if I was planning on shooting 69-75gr I'd get a 1:7 barrel.

 

[DarkRose]

All of my AR's are 1:9 twist, but then again I only shoot 55-62gr through them, if I was planning on shooting 69-75gr I'd get a 1:7 barrel.

So sounds like a 1:8 would be a decent compromise for maybe 55-65gr.

 

[DarkRose]

Another barrel question...

Just to add confusion for myself...

Had planned on a 24" bull barrel setup, what would be a benefit of a 24" over a 20"? Velocity, but would I gain that much accuracy? And with a 20" could I still use a rifle length handguard, or would I need to go to a shorter carbine length?

 

[RichardR]

Yes the 24" bull barrel will be a little more velocity which does usually equal the bullets shooting slightly faster & flatter & thus a tad more accurate at further distances.

On top of that a bull barrel is going to have more stable barrel harmonics than a standard profile barrel, this also increases the rifle's accuracy potential.

If you want even more accuracy potential out of your AR buy a 24" bull barrel made from stainless steel (non-chrome lined) & chambered only for .223 match ammunition, not 5.56 & not a Wylde chamber & get yourself a free-float hand guard to put on it.

 

[DarkRose]

Yes the 24" bull barrel will be a little more velocity which does usually equal the bullets shooting slightly faster & flatter & thus a tad more accurate at further distances.

On top of that a bull barrel is going to have more stable barrel harmonics than a standard profile barrel, this also increases the rifle's accuracy potential.

If you want even more accuracy potential out of your AR buy a 24" bull barrel made from stainless steel (non-chrome lined) & chambered only for .223 match ammunition, not 5.56 & not a Wylde chamber & get yourself a free-float hand guard to put on it.

Well I am going to do a free-float, probably stainless, but want to find a bead blasted one. 20" or 24" either one would be the heavy bull profile.