PROGRESSIVE TWIST yay or nay??

elkaholic

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I've been thinking about checking on a Bartlein barrel and I noticed they offer progressive twist. I know that's what Lazzeroni uses and they claim higher velocity because of it. Does anyone out there have any experience or knowledge on this subject?
Do any of the benchrest guys use progressive twist? Thanks in advance......Rich
 

Mikecr

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Lazzeroni's entire hook amounts to velocity. But that should not be your focus.

I got the impression about 10yrs ago that progressive twist was very common in Canada. This because, Canada was the only place you could get them at that time, and it was not a big deal there.
So today, I suggest canadian forums for real information about progressive twist benefits and costs(nothing is free).
 

BountyHunter

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Go to BR central and lot of posts on the gain twists. So yes they are using them.

Peak pressure would be lower with a slower twist at the breech, but the computer programs like quickload cannot compensate for that as they are programmed only for standard factory twist like 1-10 in 30 cal and definitely not a gain twist.

All things being equal, less peak pressure should allow slight MV advantage. It is also seen in the 5C or 5R type rifling with higher MV.

BH
 
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phorwath

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I read BountyHunter's posts all the time because he's on top of this game. You can pretty much bank on what he says being factually correct. When it comes to opinions, everyone has one, buy when he speaks factually, he knows a heck of a lot of s__t from vast experience. Suggest you PM him if you still have further questions.
 

Black Diamond 408

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I have a Bartlein 375 cal barrel that is nearly ready for testing, 16" starting twist, ending twist at 31" is 7.75" It is on my 375 snipetac chambering. I will post the results in a separate thread.

I also have a faster twist barrel in the same caliber, 12" to 6.5" twist for the extra long lathe turned solids.

Dave
 

jwp475

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Go to BR central and lot of posts on the gain twists. So yes they are using them.

Peak pressure would be lower with a slower twist at the breech, but the computer programs like quickload cannot compensate for that as they are programmed only for standard factory twist like 1-10 in 30 cal and definitely not a gain twist.

All things being equal, less peak pressure should allow slight MV advantage. It is also seen in the 5C or 5R type rifling with higher MV.

BH

Are there any presure data that indicates a lower peak pressure useing a slower twist?
 

lazylabs

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Doesn't it seem the bullet gets a lot of jacket abuse with the gain twist? I can see it working better with driving band turned bullets. I would think something like a berger driven at fairly high speeds in a gain twist would get all torn up. What am I missing?
 

jwp475

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Doesn't it seem the bullet gets a lot of jacket abuse with the gain twist? I can see it working better with driving band turned bullets. I would think something like a berger driven at fairly high speeds in a gain twist would get all torn up. What am I missing?



I agree the bullet jacket will be worked more. The rifling enfgraving wil change as the bullet travels down the barrel
 

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