Twist for 257 Bob?

I am getting ready to start ordering goodies to build a Robertson my 12 action and am wondering about twist rate. The rifle will primarily be a deer/medium game rifle with most shots where I hunt being less than 150 yards. The bullets I plan on testing in the beginning will be Barnes TSX and TTSX both 100 grain and nosler partition 115 grain. I know standard twist for most 25's is a 1:10 but I am thinking of a faster twist like a 1:9. Is there any need to speed up twist for the longer bullets at 257 Roberts velocities or will the standard twist work just fine?

Standard 10 twist should work, but if its the same price for the barrel/blank you can go with the 9 twist just to be safe. Only way I would think the faster twist could hurt you is if you were going to push light bullets close to their limits.

I am going to be that guy and ask: why the 257 Bob? Why not a 257-AI or better yet a 250-AI Savage? Since you are looking at a 150 yard gun the 250-AI would be more efficient, use less powder, have lower recoil, and (unless you run them real hot) much better brass with almost no trimming. 250-AI will give you the 250-Bob level of performance you want to boot.

Just some food for thought, but to your question either twist should work, but 9 definitely will get 'er done.

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Originally Posted by bootsmcguire

Standard 10 twist should work, but if its the same price for the barrel/blank you can go with the 9 twist just to be safe. Only way I would think the faster twist could hurt you is if you were going to push light bullets close to their limits.

I am going to be that guy and ask: why the 257 Bob? Why not a 257-AI or better yet a 250-AI Savage? Since you are looking at a 150 yard gun the 250-AI would be more efficient, use less powder, have lower recoil, and (unless you run them real hot) much better brass with almost no trimming. 250-AI will give you the 250-Bob level of performance you want to boot.

Just some food for thought, but to your question either twist should work, but 9 definitely will get 'er done.

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Roberts because I already have a bunch of ammo and brass from another Bob I let get away. Components are so hard to come by now so don't want to have to for a bunch of brass before load development can start with the improved version.

I run the the 115 bergers out of my 250s and the 10 twist does just fine.

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Originally Posted by 10gaugemag

Roberts because I already have a bunch of ammo and brass from another Bob I let get away. Components are so hard to come by now so don't want to have to for a bunch of brass before load development can start with the improved version.

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Totally respectable and economically wise decision, but here's another thought just for the sake of friendly debate.

If you are already sitting on a pile of components for the Bob, why not go with a Bob-AI? Early development can be effectively done while fireforming brass to the AI chamber. Then you will find the window your barrel likes for your chosen bullet and powder while forming, killing two birds with one stone. If after that you still have brass that needs to be formed, load 'em up with your developed load and blast away. When forming my brass for my AI chambers, I find that the accuracy is very comparable with loads made from formed brass. I tend to form all my brass while in the field hunting and during load development.

I also want to point out that brass life is greatly increased by going to an AI chamber and trimming is nearly eliminated. In my 243AI my brass life has (so far as the brass is still going strong) tripled. Since brass one of the more costly and sometimes hard to find components this can be a huge economic and hassle saving choice.

Sorry for the hi-jack as I know this thread is about twist rate and not your chosen chamber. I just wanted you to consider an AI chamber as in the long run I think you will be much happier. Either way you go enjoy and I wish you all the best of luck with it.

Almost every shooting enthusiast I know that converted a few cartridges to AI versions eventually says they wouldn't do it again because of the PITA factor with fire forming brass etc. That said, my buddy's .250 AI is his favorite and yes, it does approximate .257 Bob velocities. I'm still a .257 Bob guy, myself. I would like to have a .22 Hornet AI, though:cool:

Durwood I seem to find opinions to be in the majority of in favor of the AI but to each his own. I just have yet to find a down side to it from a reloading, cost, and performance stand point.

As to your wish for a 22-Hornet-AI feel free to start another thread (as to not hi-jack this one further) and I will share my opinions on that round as I have the 22 K-Hornet (basically if not the same to a 22-hornet-AI) and I am sure others will chime in as well.

Back on subject, thanks bootsmcquire. I've owned three .257 Robts rifles and still have one. All of mine have been factory 1-10 twists, but I think a 1-9 would be a good thing. None of my Bobs ever preferred bullets over 100 grs for accuracy.

I don't know that I would ever shoot over 100 grain as the Barnes would actually retain more weight than heavier lead core bullet but the added length of the monolithic bullet has me thinking and a faster twist certainly won't hurt a thing. As to the AI versions of cartridges, Boots you have that 250 AI in my head as a possibility in the future. Did a little research and that is an impressive little cartridge. Be a good one for the daughter.

The 250AI should provide performance very similar to the 25-06 way out performing any standard Bob out there. my standard 250s provide essentially identical performance as that of the Bob. I am able to push 100 grain match kings over 3000fps easily and 115 bergers over 2800fps with 24" tubes and imr 4064. There is nothing wrong with the standard Bob but Ackley improving it is way worth the minor hassle of fire forming.

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Originally Posted by stomp442

The 250AI should provide performance very similar to the 25-06 way out performing any standard Bob out there. my standard 250s provide essentially identical performance as that of the Bob. I am able to push 100 grain match kings over 3000fps easily and 115 bergers over 2800fps with 24" tubes and imr 4064. There is nothing wrong with the standard Bob but Ackley improving it is way worth the minor hassle of fire forming.

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I never had any issues getting a 100 grain north of 3100 and scaring 3200 with no signs of pressure with a 22'' barrel. Could have kept going but 1/2 groups kept me where I was. These are +P loads though not standard Bob loads.

If you are getting that kind of velocity with a standard Bob then just imagine what the Ackley version could do for you. Those are way faster velocities than I have ever seen out of a standard bob, +p loads or not. Especially out of a 22" tube.

I have always been able to get 3100 fps with 100gr bullets from my 22" and 20" Standard .257 Robts. H-4350 and H414 will do it as well as other powders I'm sure.