What twist, 10 or 11

[amlevin]

It's "new barrel time" for my 700 and am now "in line" for a new Benchmark Barrel.

Question is, which twist. Old barrel was a 5-R with 11.25" twist and I sure liked how it shot. I've had 1:10 recommended as well as the 1:11. I will be shooting max weight 175 gr Nosler Custom Comp's or SMK's with an occasional 178 A-Max.

Which twist rate would perform best? JBM ballistics stability calculator shows the 11 as right in the suggested range for stability factor and he 10 just outside. Since Benchmark is a couple months out for my barrel I thought I'd get some feedback.

Don't plan on shooting any farther than 1K.

 

[NateHaler]

Flip a coin. It won't matter. Use whatever your barrel installer recommends, in case the new barrel shoots poorly. Otherwise, he/she will say "Told you so".

People overthink this sort of stuff, and there's NO way to know how another barrel will shoot until it's installed.

If it was my rig, I'd go 1:10". That way, you could easily shoot the 190 grain bullets too, in case you want to. And considering what John Whidden did/does with his 1:10" Palma rifle, using 155 grain loads, you shouldn't have a problem.

But you won't know until it's on. That's the risk, and thus part of the fun!

 

[savageshooter86]

I was trying to determine same thing and Berger tech told me he would suggest a 12 twist (I told them I would not be shooting any bullet longer/heavier than the 185 hybrid)

Interesting article Salazar did where he shot a 13 twist with heavy bullets and had better results than with lighter bullets in same twist rate. I found that interesting

 

[NateHaler]

I know what you mean SS86. I think shooting results boil down to art, science, and voodoo (or luck).

 

[savageshooter86]

Whidden also thought I should be able to do ok with the 155 using my 26" 10 twist too, but didn't ever try it.

So I would get whatever twist you want to and find the load you're rifle shoots

I was under the impression too fast of twist can cause velocity loss and possibly spinning the bullet too fast? It would be interesting to read Litz book as I'm sure this is discussed further

I too looked at the Sg calculators and the 10 twist was over 2 while the 12 was right in the 1.45 range. I think 11 was in the 1.6 range

 

[DennisH]

Interesting article Salazar did where he shot a 13 twist with heavy bullets and had better results than with lighter bullets in same twist rate. I found that interesting

I was also impressed with his above article.

I put 4K rounds down a 28" 12 twist 308 mainly shooting 190 vld's. I won several match's with this barrel.

I currently have a 10 & 11 twist 308. Both seem to be just as accurate.

I have shot 110's out of my 10 twist and they were very accurate, short range. Never tried them past 250yds.

 

[amlevin]

I was under the impression too fast of twist can cause velocity loss and possibly spinning the bullet too fast?

That's what's been confusing to me. I've heard of velocity loss and more often that the bullet could "explode" and not reach the target if over-spun.

The one that seems to come up from time to time, and perhaps makes more sense, is that a bullet that is "over stabilized" will want to maintain the same attitude as it travels down range. It would essentially follow the trajectory much the same as a landing airplane, in a stall, with the nose increasing the drop due to velocity loss.

Is this true? The article I read made sense but does it actually occur in heavy bullets traveling less than 3k fps???

 

[jsthntn247]

I would go with the same barrel you had on it if you liked it that well. A 11.25 will stabilize up to the 185's easily. You said you are waiting on a Benchmark, try 3rdgenerationshootingsupply, they keep some in stock and you might not have to wait

 

[amlevin]

I would go with the same barrel you had on it if you liked it that well. A 11.25 will stabilize up to the 185's easily. You said you are waiting on a Benchmark, try 3rdgenerationshootingsupply, they keep some in stock and you might not have to wait

Thanks. Benchmark is right down the road from me, literally, and they're doing the rebarrel job with complete truing.