20 VT twist rate

[shaun1826]

I’ve read a bunch of threads on this. I plan to use a barrel in the 18”-20” range.

Is there any downside/accuracy loss going with a 11 twist instead of 12 twist for the 32 vmax to 40 vmax bullets?

Is there any downside/accuracy loss going with a 10 twist instead of 11 twist for the 32 vmax to 40 vmax bullets?

What about a 9 or 8 twist if I want to play with 55 bergers in addition to the 32-40’s? I talked to Hornady and they said the 32 and 40 vmax is good in the 10-14 twist range. They probably have a little factor of safety built in on the fast twist side though so maybe a 9 twist would work?

 

[Hotshot]

That cartridge in a short barrel rifle will be fantastic with 32grain bullets. Go 11 twist and have loads of fun.
If you want to shoot heavier bullets choose a higher capacity cartridge and use a longer barrel.

 

[B23]

If you want to fully stabilize the Berger 55's in 20VT with18-20 inch barrel setup which will probably launch them in the 3000-3100fps range I'd use an 8tw.

But, like Hotshot suggested, I'd slap a 10 or 11 twist on and shoot the 32-40gr bullets. Unless you just wanted to shoot the 55's, "because", I don't really think there's much if any benefit. Maybe if you're trying to develop some sort of quiet subsonic 20 cal to shoot suppressed the 55's would make that task easier but even that would be kind of a stretch.

Generally, people shoot the 55's in larger case capacity cartridges like the 20BR, 20-250, 20x47Lapua and others.

 

[TAJ45]

Imo, loss of accuracy going from 11 to a 10 tw will be negligible if any. If a button bbl, the 10 should provide a cushion in case it comes out a 10.5.....and don't ask me how that works but it can happen. If someone would work up a long 45gr, you should be able to handle it along w any 40s hands down. Velocity loss should be single digit from what I've read.
The extra rpm may give some extra terminal performance as well.

 

[Ledd Slinger]

I’ve read a bunch of threads on this. I plan to use a barrel in the 18”-20” range.

Is there any downside/accuracy loss going with a 11 twist instead of 12 twist for the 32 vmax to 40 vmax bullets?

Is there any downside/accuracy loss going with a 10 twist instead of 11 twist for the 32 vmax to 40 vmax bullets?

What about a 9 or 8 twist if I want to play with 55 bergers in addition to the 32-40’s? I talked to Hornady and they said the 32 and 40 vmax is good in the 10-14 twist range. They probably have a little factor of safety built in on the fast twist side though so maybe a 9 twist would work?

You would never catch me running a 14 twist in 20 cal for anything, especially 40gr.

No accuracy loss with 11 twist. In fact the 11 seems to be more accurate and forgiving than 12 twist across the board with bullets up to 40gr. 11 is arguably the best all around twist rate for excellent accuracy in 20 cals with the majority of bullets readily available.

I have a 10 twist on a 20 ppc that I’m starting to play with so no official verdict on that one from me personally yet. Testing 39gr and 40gr in it at the moment.

9 twist and faster is getting into the point where you are only going to get the best accuracy with heavier bullets so if you ever plan on using lightweight bullets 34gr or less, I would choose something slower. 8 twist is of course even further into the point of no return. Not saying the fast twist barrels won’t shoot lighter bullets well, but they probably won’t be as forgiving with narrower accuracy nodes. I can get lightweight 6mm Varmint bullets to shoot pretty dang good in my 8 twist 6mm barrels on various chamberings but they are harder to tune in than the heavier bullets the 8 twist was designed for.

 

[Prose]

The extra rpm may give some extra terminal performance as well.

100% With the shorter barrel I'd do a 10 twist. That way the loss of velocity is equaled out with rotation.

 

[Tommie]

I talked to Hornady and they said the 32 and 40 vmax is good in the 10-14 twist range.

You sure about that?

 

[Ledd Slinger]

You sure about that?

Yeah Hornady reps are actually that dumb. Lol!

 

[shaun1826]

You sure about that?

That’s what the man in the tech dept. said. He pulled it up on his computer or had a manual he was referring too.

 

[Ledd Slinger]

I don’t even know a barrel or rifle manufacturer that makes a 20 cal in a 13” or 14” twist because they know better than to twist slower than 12”. For a rep or company to even suggest anything slower is nothing more than complete ignorance from inexperience.

You can shoot 40gr in a 12” twist but an 11” is better.

 

[shaun1826]

Thanks guys! I went with an 11 twist.

 

[B23]

Thanks guys! I went with an 11 twist.

Good call! Now all you have to do is stop worrying about chasing velocity, over thinking the freebore thing and you'll be fine.

 

[Ledd Slinger]

Unless you are shooting Berger 55’s or an off brand heavy bullet over 40gr, there’s no need for any freebore in the chamber. All my bullets are 40gr or less anymore so all my chambers have “0” freebore