Dumb Question Time - Barrel Twist Ratio

[Shynloco]

Ok folks...since accuracy is my thing, I thought this would be the appropriate place to post this question. I shoot strictly paper and shoot mostly at 100 yds because of the local range availability. I have a Ruger M77V with a bull barrel that has a twist ratio of 1:10 that shoots incredible 5 shots groups, mostly around half the size of a dime. I'm thinking about changing the barrel out to a Sheilen, but was wonder if changing to a faster twist ratio would have any negative affects on accuracy even with changing to the corresponding bullet weight necessary for that twist? Any thoughts?

 

[Kenny474]

The 100yd BR guys shooting the 6ppc's usually use a between a 1-12 and 1-14 twist because it is said the slower the twist, the better the accuracy at short range.

The longer bullet used in a 1-8 twist will actually spend more time in yaw and negatively effect group size. This is also why point blank BR guys use flat base bullets instead of boat tails, as the flat base is said to yaw less as well. And since most longer bullets for the faster twists are boat tails designed for longer ranges, you may also effect accuracy that way as well.

It's not to say a fast twist barrel can't be accurate at 100yds, because they can. But usually not to the same point a slow twist 6ppc or 6BR will be.

You could still use the shorter flat base bullets in the faster twist, but the over-rotation will cost you a small amount of accuracy.

All I am trying to say is that a slower twist with shorter flat base bullets will usually produce the best groups. We are not talking a huge amount, but the difference between winning a match and coming in 10th if you were competing. It will likely cost you a bit, but we are talking hundredths of an inch here in all likelihood. Not going from .2's to .8's or anything. But it will cost you something in most cases.

Kenny

 

[fdshuster]

shynloco: In addition to all the good info from Kenny, there is some thought that since the faster twists are spinning up the bullets at a higher rate, any minor flaws in the bullet will become more critical for accuracy. If you have a dedicated rifle for shorter distances only (max 300 yds?), then a slower twist may be the better choice. I personnally use the lighter weight bullets only at 300 and closer, keeping the mid and heavyweights for everything beyond 300 yds. Just my opinion, but I can't see using a 107 gr. ( for example) in the 6BR, 8 twist at 100 or even 200 yds. Sorta seems like overkill.