Barrel Twist for a .204

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Kimberguy2004

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I just ordered a barrel for an AR build. It's going to be chambered in 20 Practical, which is a standard .223 case necked down for a .204 bullet. I ordered the barrel with a 1:10 twist. My intent is to shoot nothing heavier than a 40gr bullet. Am I OK with that twist rate, or should I call and change the order? I have plenty of time since there's a 16-20 week delivery time for the barrel.. I just want to get a twist rate that's going to be optimal for 32-40 grain bullets..
 
You would be fine with a 12. 10 won't hurt anything though
 
Most of the guys that are focusing on the 50 grain Berger go for the 1 in 9. Rumor has it there might be a 55 Berger coming but personally I'd want more case capacity than the .223 for something that heavy.
A lot of the 1 in 12's seem to have problems with the 40 V-Max so a 50 grainer might very well not stabilize in a 1 in10.
I had a .20 Dasher built with the 40 V-Max as a target bullet and I used a 1 in 11, it exceeded my expectations totally. At my altitude with the capacity of the Dasher I think it might well handle the Berger 50's too. That was a topic of discussion with the smith myself and a friend who did a 1 in 9 .20 Dasher in Colo. at the same time I did mine.
That's the long way around the barn to say I agree completely that a 1 in 10 will consume all the various 40's with relish, probably ok on 50's especially at a bit of altitude and a coin toss on 32's (I'd guess not so great on 32's).
As about all I shoot is .17's and .20's though I sure would be interested how it comes out for ya.
 
I seriously doubt that I will shoot 50 grain bullets. I'm baseing my project on a rifle that was built by Robert Whitfield and featured on 6mmBR.com. He used a barrel with a 1:11 twist and the rifle did well with both 32 & 40 grain bullets. That's why I'm wondering if both sizes will be OK in a 10 twist barrel. That's what was suggestd by John at White Oak when I called to order the barrel. If general consensus is that a 11 would work beter for those two weights than the 10, it's not a problem to change the order, since there's a possible 20 week wait for it. I did call Mr. Whitfield, but understandably, he wasn't receptive to giving me any advice since he builds and sells AR uppers.
 
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If I were going to include the 32's in the mix I'd go with the 1 in 11. As I mentioned it appears a fair number of 1 in 12's don't like the 40 V-Max but the 1 in 11 gives a little added insurance for them (at least that's why I chose it). The 32's do real well in the 1 in 12's but I'd be amazed if a 1 in 11 spun em to fast to function (a 1 in 10 yes possibly).
I live at 5,200ft of elevation and I have 6 or 7 different wildcat .20's with 1 in 12's, I've yet to have one of em not shoot the 40's at least acceptably (some real well). All of my 1 in 12's dote on 32's.
All that is the reason for the 1 in 11 in the Dasher just a little extra insurance as I mentioned. With the velocity I get out of the 40's I've not experimented with the 32's.

KillerBeeswarmvs-1.jpg


I can't imaging what velocity the 32's would get but why? The BC on the 40's is so much better it outperforms the 32's 7 ways from Sunday.
I've heard some whose rifle doesn't care for the 40 V-Max call it an inaccurate bullet. hogwash!

That chrono tape picture was taken on this group.

-12.jpg


This was from my first day testing the 1 in 11 .20 Dasher and believe it or not it's not the best group I shot. Not the worst either :eek:.
My rifle is well put together so I expect that kind of accuracy but it does make a statement about at least this particular 1 in 11 with 40's.
As a totally personal opinion I'd also state that in the Bigger .20's like the .204, .20 Tactical, .20 Practical, .20 BR etc you are well served with the ballistic advantage of the 40's as opposed to the 32's.
Real sorry for being so windy.
 
Kimberguy2004 I sent you a message but not sure how the P.M. system works.
 
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