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gregshin

Best barrel twist rate for 147gr and 124gr bullets

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I'm in the market for a new barrel.

That being said i rarely take shots out to 50 yards...but if I have to and since i need a new barrel anyways why not ask the question before buying.

I looking around for barrels and noticed that schuemann is pushing a 24 gain twist...has anyone user 147gr and 124gr bullets with this twist?

I'm just better off with using a 16 gain twist since load mostly147gr bullets?

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For 9MM you want a 1 - 10 twist barrel. S&W initially went with a 1 - 18 twist in their M&P and have since moved to a 1 - 10 twist, CZ also rubs 1 - 10 twist barrels as does Glock and Tanfoglio. My M&P with a 1 - 18 twist struggled to stabilize my 147 gr cast bullets. Since making the change no problems have been experienced. 1 - 24 seems pretty slow to me.

Take Care

Bob

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My Schuemann 1:24 gain twist would shoot anything. But it had to be really, really fast (velocity) to be accurate. My slow (1:32ish) twist KKM will shoot 147gr bullets, but that's not what I shoot through it.

I'm not aware of any available 1911 barrels with a 10 twist. I've seen mention of them in some Bullseye circles, but they are custom and not available as far as I know.

I would go with a Barsto (1:16), Clark, or KKM barrel (standard twist which is in the 1:24 range). I don't see a need for gain twist.

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After conducting significant ransom rest testing with my G34, I determined that my KKM barrel would not group well with anything over 125/125 grains. I even tried pushing 147's really hard (+1000 fps) with the KKM to no avail. The stock Glock barrel shot all bullet weights well, with 147's being the most accurate in my testing. YYMV.

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I'm not aware that KKM publishes the twist rate of its Glock barrels. I emailed KKM a couple of years ago asking about the rate, but didn't get a straight answer. I've seen speculation that they are anywhere from 1:16 to 1:32. Based on my testing, I would guess that it is greater (slower) than 1:16.

Edited by ActionJackson

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Perhaps Im misunderstanding but I would assume that a lower twist rate would equate to better accuracy. However Im seeing stock barrels mainly come in 1:10 ratio and then higher twist rates for aftermarket match barrels such as Bar-sto having a 1:16 twist. 

 

How is the weight of the bullet projectile determined compared to the twist rate? 

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48 minutes ago, PhillySoldier said:

Perhaps Im misunderstanding but I would assume that a lower twist rate would equate to better accuracy. However Im seeing stock barrels mainly come in 1:10 ratio and then higher twist rates for aftermarket match barrels such as Bar-sto having a 1:16 twist. 

 

How is the weight of the bullet projectile determined compared to the twist rate? 

It's not really the weight, it's the length of the bullet that determines the minimum twist that will stabilize the bullet. Longer bullets are heavier so most people refer to it by weight.

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KKM says their standard twist is 1:18.  If you want to shoot 115gr bullets accurately, you do not want a 1:10 twist.  That will over-stabilize the bullet and cause problems unless the bullet is perfectly shaped.

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On 6/1/2018 at 10:02 AM, zzt said:

KKM says their standard twist is 1:18.  If you want to shoot 115gr bullets accurately, you do not want a 1:10 twist.  That will over-stabilize the bullet and cause problems unless the bullet is perfectly shaped.

 

In rifles, there really is no such thing as over stabilized. I can shoot  50gr to 52gr match bullets just as accurately as a 77gr in a 1-7 twist 22 cal barrel.

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Too much thought and talk already gone into this.  Get the Shuemann barrel, or the Bar-sto, or the KKM.  Can't fault you wanting a top-notch barrel -- they're sexy -- but you're not going to see a bit of difference for the twist rate for what you're shooting.  16, 24, 32... whatever.  Get the name you feel is sexiest.   If there were a definitive answer to your question, all the manufacturers would using the same twist rates.  Think about it.  ;)

A rifle bullet that is over-stabilized is going to resist the turn of the nose toward the ever-changing bullet path, but you want the nose to constantly change to follow the bullet path to minimize surface area directly affected by forward air resistance and the pressure wave ahead of a super-sonic projectile.  For an overstabilized bullet that is NOT doing that, it effectively reduces its ballistic coefficient.  In that case, gyro-stabilization is keeping the nose "up" or at least not letting it follow as fast as is optimal.   


Not really sure what the big whoop is with 9mm at pistol distances.  Unless you're trying to shoot 115gr cast lead fast enough to make 9mm major in a 1:10 twist barrel, which might tear the bullet apart, then even 1:10 isn't going to over-stabilize the bullet in a way that's going to cause a problem.  

 

Get the barrel from the manufacturer you've always fancied most.  You're not going to be disappointed.

Edited by IDescribe

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I had a similar question (rifle related) and sent Sierra an email inquiry specifically referencing one of their bullets.  They were very kind and sent me a thorough answer.  I’d suggest you ask them, but to summarize what they are probably going to tell you: if it’s a quality bullet that can withstand a high rotational rate without breaking apart, you’re not going to go wrong with a faster twist rate, even if it “over stabilizes” the bullet.  

 

Also, I can tell from some of the comments above that some folks don’t understand twist ratios.  1:16 means it rotates once every 16 inches.  1:10 means it rotates once every 10 inches.  Therefore 1:10 is faster than 1:16.  The smaller the second number, the faster the rotation/rwist rate.  Longer bullets do better with faster twists but generally speaking, quality bullets are fine being over stabilized.  Having said that, no bullet will do well if it is under stabalized.  

 

In my comversation with Sierra, though, I was genuinely shocked at how slow of a twist rate would stabilize the bullet I was asking about.  Specifically, their 135gr .308 SMK can stabilize with as slow as a 1:25 twist barrel!!!!   They said to go with a 1:8 and don’t sweat the so-called over-stabilization.  So.... choose faster if you can, but if you can’t, then don’t worry too much about it.  You’ll likely be fine either way.  

Edited by jkrispies

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