Which twist rate for 20 Practical

[floydboy]

I am in the process of building a 20 Practical and can't decide on a twist rate. It will be a 24" SS Green Mountain blank on a savage receiver from Apache. It seems when the cartridge first came out a 12 twist was the norm. Now some are shooting 7-8 twist. I'm positive I don't want to go that fast of a twist. I have a 22-250 for long range shooting and was wanting this gun for mainly 200 yds and closer plinking and hunting. I'm thinking the 32 gr bullets will work fine for that range and want the most accurate set up I can put together for that purpose. I still want to give myself the chance of shooting the 39 and 40 gr bullets if possible.

I was going to get a 12 twist to push the little bullets but recently have been leaning towards a 11 twist to give myself the added insurance of shooting the heavier ones if I want to. If the 12 will do a much better job with the 32 grs I will stay with it. If there isn't much difference between the 11 and 12 twist on the lighter bullets I might as well go with the 11.

What do you guys think?

Thanks,,,Floyd

[sharpshooter]

Go with a 1-9, it will shoot any bullet made.

[hafejd30]

I think there a coupe for sale in the classifieds right now if your interested

[darkker]

twist is about RPM and stability for a bullet LENGTH, weight has all but nothing to do with it.
A 9-twist will destroy all but the hardest "light weight" bullets out there. So you would have to run them very slowly.
If peace of mind is what you want then use the 11.

Light jacketed bullets such as the TNT, Dogtowns, Varmint Nightmares, all have an RPM limit of approx 250,000 RPM. The hardest, or truly Thickest jackets out there, will take something on the order of 320,000 RPM. How smooth your barrel is will weigh greatly on the absolute number.

RPM = MV * 720 / twist.
So for an example:
3,800 fps * 720 / 11 twist = 248,727 RPM

[bc83]

I have 1-9 twist love it

[sharpshooter]

I've never had any trouble with any weight bullets coming apart in a 1-9 twist. I've pushed 55 gr. Bergers out of a 20x47 Lapua @ 3875 fps, and 40 gr.BT's @4300 fps with no problems.

[floydboy]

I bought one of BTSnipers barrels. Thanks for the imput.

Floyd

[darkker]

I've never had any trouble with any weight bullets coming apart in a 1-9 twist.... and 40 gr.BT's @4300 fps with no problems.

Right, which is @ 340,000 RPM. So as I said, "Your barrel smoothness will weight greatly on the final number".
You either have an exceptionally smooth barrel, but are close to the limit. Or work for Nosler, and don't believe centripetal force exists:cool: