What twist for .50?
 

Well, I finally decided I'm going to order a custom .50 barrel for my Pro Hunter from SMI. I sold a few guns and was going to try to get started in bowhunting, but I don't think I would like shooting a bow as much as much as a gun. I was (and still am a little) hesitant to spend the money on a custom barrel, but finally just decided it's a one time thing and might as well do it and have fun with it.
So, I can order about whatever twist I want. I read where guys have gone with as fast as 1 in 22" to as slow as 1 in 32", which is the SMI standard twist. I plan to shoot 250 to 300 gr. primarily but I'm sure I'll shoot some lighter and some heavier. The 300 gr. SST's I have are exactly 1" and using the Greenhill formula I would actually want something close to 1 in 35" but that seems too slow. I was thinking 1 in 24" but really don't know.

FWIW, I wonder if that formula is applicable to sabots. The sabot is what is gripped by the rifling and imparts the spin to the bullet. Just thinking out loud.

I wondered the same thing. I did try it with a 45 bullet, and it's only a couple turns faster.

Every twist is a compromise. I think the 1 in 24 twist is a good one in a 50 for longer bullets. That twist can shoot shorter saboted bullets as well. Sabotloader has proved this. The 1 in 28 has been used a lot and shoots very accurately also. I would go with one of those two and I would lean towards the 1 in 24.

Well since i own a Douglas 1-32, a Savage 1-24 and have owned numerous 1-28s, i can say you probably wont see a difference unless you try shooting light weights in the 1-24. My 1-32 shoots 225gr-275gr 45cal bullets (Including Barnes) with exceptional accuracy. Ive even shot the 325gr FTX with "ok" results.

That being said i would likely go with a 1-28 if i was ordering a custom twist just because it works good with the largest variety of bullets and probably even powders. One things for sure my 1-32 LOVES the 225gr 45LC XPB and so does my shoulder at SML speeds in the NULA.

I would have thought the 1 in 32 would have been to slow for the lighter 225 gr. I have a couple different varieties of 225's that I was hoping to shoot.
I was actually just thinking that I might go with 1 in 26". I don't know if it's just because it's half way between the two extremes or something else, but for some reason it seems like a good choice.
Any reason it wouldn't work?

I think you got it backwards.

A heavier bullet usually prefers a faster twist. The 1-32 shoots the 45cal 225gr Barnes and XTP VERY well even at over 2300fps. The Savage's 1-24 usually doesn't like to shoot light weights that fast. I pretty much only shoot the 325gr FTX in my Savage and sometimes the 275gr XPB made for 460S&W.

I think you're right, don't know what I was thinking.
Perhaps then I would be best off just going with the 1 in 32" and figure if that's what he usually builds his barrels in than he probably knows what he's doing.
I don't think I'll shoot anything lighter than 225 and probably not anything heavier than 325, maybe 350. Should work, right?

It should work fine. Mine is a Douglas 1-32 on the NULA and even though i was skeptical, the first range day removed all doubts. Recoil was pretty stiff with the 325gr at 2196fps but wasn't bad with the 225gr-275gr slugs.

On MM there is some load data for both SMI and NULA Douglas barrels including an Encore or two. It appears most of the common deer hunting bullets do just fine. The 225gr XTP bullets are my fun bullets and cheap too.

I would order it in a 1/26" barrel.

If i was you i would seriously consider a 45 barrel over a 50. Like everyone said, your not going to see much difference in your twist rates in the 50cal. A 45 in a 1/20 twist opens up a lot of new opportunities for you.