Transitional/Progressive/Gain Twist Barrels aid in accuracy?

[CB11WYO]

Dad was looking into a Gain-Twist barrel and one particular manufacturer mentioned the greater potential for accuracy due to the following... As the bullet progresses down the bore and meets ever increasing resistance due to the ever tightening twist the barrel is pulled steadily forward therefore reducing barrel whip/harmonic inconsistencies.

This particular manufacturer said they typically only "gain" 1" breech is 1:10 and muzzle is 1:9

Makes some sense inside my brain bucket at least... What say ya'll? Any experience with gain twist barrels? What other pros/cons are there to gain twists?

Thanks guys.

-Clint

 

[elkaholic]

Dad was looking into a Gain-Twist barrel and one particular manufacturer mentioned the greater potential for accuracy due to the following... As the bullet progresses down the bore and meets ever increasing resistance due to the ever tightening twist the barrel is pulled steadily forward therefore reducing barrel whip/harmonic inconsistencies.

This particular manufacturer said they typically only "gain" 1" breech is 1:10 and muzzle is 1:9

Makes some sense inside my brain bucket at least... What say ya'll? Any experience with gain twist barrels? What other pros/cons are there to gain twists?

Thanks guys.

-Clint

I thought about it and then changed my order to a std. twist. I did some checking around and found that almost NO competitive shooters use it. This is usually a good place to check and see what works. Also, a gain twist will change (widen) the groove cut in the jacket as it progresses down the bore. I'm not sure that is a good thing. I have heard of SLIGHTLY increasing the twist right at the muzzle, but that is to make sure that there isn't any of the opposite affect on the barrel (less twist which is definitely bad!) Bottom line; a barrel with very consistent bore and twist can probably not be improved on and anything else is likely a band aid approach! Sort of like pressure on the fore end to correct a bad bedding job..........Rich

 

[J E Custom]

The gain twist has been around since before WW 2 and many experiments and trials have been performed to find out if it was a better system of rifling. (In theory, it seams to be the answer to many of the problems the bullet has to deal with). but no one has ever proved that it was better and in fact, some opinions are that it is not as good as standard rifling.

In manufacturing barrels, most are slightly smaller on one end than the other (.00001 to .00005)
and most of the barrel makers will mark the small end so it can be installed at the muzzle. (The
theory is that as the bullet goes down the barrel and some of it is worn off on the lands and grooves , it will remain tighter for better accuracy) again, just another theory that is hard to prove.

With ultra high velocity, it makes sense to start the bullet slower and increase twist as it proceeds down the barrel to lower the chance of jacket separation from the core. But with bonded core bullets and monolithic solid bullets, this problem has been minimized .

I do think if it was even slightly better It would be in most if not all match rifles.

Just an opinion

J E CUSTOM

 

[Mike 338]

I smell a million dollar grant. It's for the children.

 

[lazylabs]

I have been trying to decide on a 375 barrel, standard or gain. If you want to only shoot bore rider driving band kind of bullets with real high BC and maybe see a gain past 1k there might be something to be had. The down side is lack of flexability.... For me locked into 2/3 CE bullets for about $1200 invested in the trial.....hummmm.

I dont believe the argument about not seeing them used in match shooting. If there were some 3 shot 1500 yd matches you might. The bullets and cases that benefit the most dont lend themselves to fit the current match requirements. It would take about 2 ten shot fast relays to ruin a 408 based barrel.

 

[J E Custom]

I like to think outside of the box and had considered gain twist for several builds. so first I read everything I could find on it by experts and could not find one single source that could/did prove
it was an improvement in any bullet weight or size some of this testing led to the smooth bore
and fins on bullets(They proved to be better than any kind of rifling).

Size has nothing to do with the effectiveness of the gain twist rifling, in fact this was where it was thought to do better, because in theory it would solve some of the problems with shear.

It was tried in the really big guns because it was thought that the starting inertia of bullets weighting 3,000 or 4,000 lbs + was one of the accuracy problems. It didn't help/improve the accuracy.

More lands and groves and slower twist was the best.

On the bigger bore rifles .375 to .510 a 6 or 8 groove 14 or 15 twist is recommended.

Gain twist sounds good, but it has yet to be proven as good or better than regular/conventional
twist, At least to me or I would have several rifles with it.

I am not against it, In fact, I would like to see more people try it and post the proof that it was better.

Just an opinion.

J E CUSTOM

 

[Deleted member 46119]

...

More lands and groves and slower twist was the best.

On the bigger bore rifles .375 to .510 a 6 or 8 groove 14 or 15 twist is recommended.

Gain twist sounds good, but it has yet to be proven as good or better than regular/conventional
twist, At least to me or I would have several rifles with it.
...

Just an opinion.

J E CUSTOM

I am considering changing the next build from 375 down to 358. This since CEB makes and will make high BC 358.

I've been asking one of the forum sponsors about gain twist for the 358 in PMs and on threads. Nothing yet but it's not a hurry.

Your comment and opinion is very helpful. I was leaning toward less grooves.

Would you be willing to put forward advice IIWM (if it were me) opinion on barrel specs for the https://cuttingedgebullets.com/cgi-bin/commerce.cgi?preadd=action&key=MTH_E01 or slightly shorter in the 300 to 320 grains range.

I'm still not settled on the case design:

• CheyTac based is bigger than I want for this bullet and per Joel Russo, not accurate as the 338-408
• 26-Nosler is smaller than I want for this bullet
• RUM based will be sooooo loooong, well so is the 338-408
• 378 Wby based has a belt
• "PRO" based is smaller than I want for this bullet
• "MJOLNIR" based is just about right but...

I don't want to step on Swamlords toes. When I tried to talk to him before the word "proprietary" came out so I bowed out.

Since then I've designed my own that is scaling up the dimensions of the 26-Nosler for the 500 Jefferies parent case.

 

[Edd]

I think a 338 Lapua Improved case would be perfect for a 358.

 

[Deleted member 46119]

I think a 338 Lapua Improved case would be perfect for a 358.

You mean like this?

 

[Edd]

That's real close.

 

[Deleted member 46119]

Yes, this would actually meet my performance goals.

The 500 Jefferies based is my preference though Jamison brass is very dear.

 

[Deleted member 46119]

That's real close.

I don't want 40degree shoulders on large cases. Just me....

 

[FearNoWind]

... one particular manufacturer mentioned the greater potential for accuracy ...

"Potential" only means, IMO, that a possibility may exist. Like the kid who has potential to be a great artist but never develops the skills. I've never found any truly professional laboratory test data that offers proof of improved accuracy from gain twist barrels. That makes me sceptical. Until I see double blind study data to support the "theory" I'll stick with a well made conventional model. Today's favorit on my menu is the Bartlein 5R.

 

[Edd]

I don't want 40degree shoulders on large cases. Just me....

That wasn't what I meant. I don't like 40° shoulders either. Unless I could buy that brass already formed, I would want a little less body taper.