Twist rate 358 Win….1:16 vs 1:12

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jmiller
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Twist rate 358 Win….1:16 vs 1:12

Post by jmiller »

Not really a lever gun question, but I need the experts help here. I just bought a barrel for my TC Encore this last summer because I wanted something more than a .357max. My Max bbl shoots great, but it’s range is limited to around 150 yards for bullet performance even though it’s capable of hits out to 200 yards with a high degree of accuracy. I bought an SSK 20” barrel with a 1:12 twist and a muzzle brake. After several trips to the range I’m really impressed. This barrel is as accurate as some varmint guns I’ve owned in the past. I’ve done nothing to enhance its accuracy, no fitted pins, no hanger bars, no fitted forearms, no nothing. The last three five shot groups at the bench were .4”, .4”, and .8” at a measured 107 yards. Honest truth. Anyway, my buddy wants to buy one pretty bad but TC is no longer in business and frames and barrels are in short supply and getting a premium price. My MGM .357max barrel can be rechambered by MGM to .358 Win, but it’s a 1:16 twist. So, what’s the real world difference between the two twists? I’m shooting 180 and 200 grain bullets in my SSK barrel. Will there be a problem with the 1:16 twist? I’ll sell him my 16 twist barrel and one of my frames but I don’t want him to get a “pig in a poke” if I can avoid it. Any experienced thoughts? I could use some help with this one. Thanks
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CowboyTutt
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Re: Twist rate 358 Win….1:16 vs 1:12

Post by CowboyTutt »

JM, welcome back, long time no see! I have no experience with a 1:16 twist for the 358 Winchester as my only rifle chambered in it (BLR) uses the same 1:12 you have with a 20" barrel length. Obviously the 1:16 could not stabilize as long a bullet as the 1:12 twist, so it will depend on what bullet he is meaning to use. Here are two calculators I have been using recently, one using the original Greenhill formula and the more modern Berger one for BT bullets. The Berger site also has access to a better calculator when not using a BT bullet that is designed for flat based bullets.

https://www.vcalc.com/wiki/AndrewBudd/G ... Twist+Rate

https://bergerbullets.com/twist-rate-calculator/

There is also the Miller formula and the "full form" of the Greenhill formula (its here I have to say you taught me something here today by doing more research on the subject of twist calculators!)

https://en.wikipedia.org/wiki/Miller_twist_rule

So, basically, if your friend is going to use a lighter bullet, he might very well be OK, if his bullets pass the various calculators out there. If he's going to shoot the heavy weight stuff of 250 grain bullets, like me? I would hesitate and do research before I went with the 1:16 twist.

Hope this helps some small way.

-Tutt
"It ain't dead! As long as there's ONE COWBOY taking care of ONE COW, it ain't dead!!!" (the Cowboy Way)
-Monte Walsh (Selleck version)
JFE
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Re: Twist rate 358 Win….1:16 vs 1:12

Post by JFE »

I have a Marlin in 35Rem and the twist rate is 1 in 16”. That rifle accurately stabilises cast FN pills that weigh 250gr. It’s really about the length of the bullet. A cast FN pill is relatively short. Obviously all copper pills are longer than conventional cup and core jacketed bullets, so the slow twist might have difficulty stabilising even lower weight copper pills.
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CowboyTutt
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Re: Twist rate 358 Win….1:16 vs 1:12

Post by CowboyTutt »

I totally agree with you about bullet length when talking lead bullets, but there is a correction factor built into some of the calculators for other metals too that needs to be taken into account, which you mentioned like when using monolithic copper bullets for example. I think the 1:16 barrel would probably work fine for most bullets that people use, but I would want to check on it beforehand if I were the one purchasing the new 1:16 barrel. Thanks for the "real life" experience, that is very useful information!

-Tutt
"It ain't dead! As long as there's ONE COWBOY taking care of ONE COW, it ain't dead!!!" (the Cowboy Way)
-Monte Walsh (Selleck version)
jmiller
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Joined: Sat Jan 10, 2009 11:40 pm

Re: Twist rate 358 Win….1:16 vs 1:12

Post by jmiller »

I’ve got a lifetime supply of Speer HotCore 180g and Hornady 200g Spire pt bullets. Those are what I’d like to use in the MGM bbl. I’d be putting another two hundred bucks into the MGM bbl by rechambering it to .358 Win and adding a threaded muzzle for a brake when I send it back for the work. I’m just trying to see if it will probably work “OK” before getting anything done. I’ll probably never use anything else in it by choice. So far it sounds like the 1:16 might be OK?
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CowboyTutt
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Re: Twist rate 358 Win….1:16 vs 1:12

Post by CowboyTutt »

Jay, I think so yes, but send me bullet dimensions as specific as you can, and I will run them for you. Might not be until Tuesday however as I am traveling.

-Tutt
"It ain't dead! As long as there's ONE COWBOY taking care of ONE COW, it ain't dead!!!" (the Cowboy Way)
-Monte Walsh (Selleck version)
JFE
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Re: Twist rate 358 Win….1:16 vs 1:12

Post by JFE »

Another example to consider is the 35Whelen in the Rem 7600 and M700. Both models were equipped from the factory with a 1in 16” twist barrel and Rem factory loads could be had with 200gr PSP and 250 PSP pills.
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