Just reading through the thread on lowlights new rifle and noticed the barrel provided by Bartlein is a gain twist, or "T" style. A quick search came up with some short mention of this but not much explanation. Can anyone explain the credible advantages of doing something like this or point me to some good reading on it? It's new to me and I'm just curious to learn more about it. My guess is that it could help keep pressures lower but maybe there's more to it than that for all I know.
Gunsmithing Theory behind gain twist barrels?
- Thread starter bdubb
- Start date
From what I have been told, a gain twist is great for bench style target rifles, when looking for just a X-moa rifle at short distances. A lot of bench rest shooters I know in my area have these on a few of there guns but they hardly ever pass 300+yd and these are rifles like a .222, .243, and a few other 6mm calibers..
And while my knowledge is lacking on the actual contributions these make, my understanding is that if your looking for something long range and competitive at longer distances, don't use them. It tightens the twist to give it more stability at the end to cause less wobble and tumble effect to my knowledge...
Rifling - Wikipedia, the free encyclopedia
And while my knowledge is lacking on the actual contributions these make, my understanding is that if your looking for something long range and competitive at longer distances, don't use them. It tightens the twist to give it more stability at the end to cause less wobble and tumble effect to my knowledge...
Rifling - Wikipedia, the free encyclopedia
Gain twist (from what I have read in the past) in theory engraves the projectile "gentler" and tends to strip it less when engaging the rifling.
Projectiles that have a narrow driving band seem to benefit from it ( Howitzers, cannons , etc.)
Wiki-
Gain-twist rifling
Gain-twist rifling begins with very little change in the projectile's angular momentum during the first few inches of bullet travel after ignition during the transition from chamber to throat. This enables the bullet to remain essentially undisturbed and trued to the case mouth. After engaging the rifling the bullet is progressively subjected to accelerated angular momentum as burning powder propels it down the barrel. By only gradually increasing the spin rate, torque is spread along a much longer section of barrel, rather than only at the throat where rifling is eroded through repeated rifling engagement.
Gain twist rifling was used as early as the Civil War. Colt Army and Navy revolvers both employed gain twist rifling. Gain twist rifling, however, is not as simple to produce as uniform rifling, and therefore is more expensive, and seldom used in commercially available products.
Projectiles that have a narrow driving band seem to benefit from it ( Howitzers, cannons , etc.)
Wiki-
Gain-twist rifling
Gain-twist rifling begins with very little change in the projectile's angular momentum during the first few inches of bullet travel after ignition during the transition from chamber to throat. This enables the bullet to remain essentially undisturbed and trued to the case mouth. After engaging the rifling the bullet is progressively subjected to accelerated angular momentum as burning powder propels it down the barrel. By only gradually increasing the spin rate, torque is spread along a much longer section of barrel, rather than only at the throat where rifling is eroded through repeated rifling engagement.
Gain twist rifling was used as early as the Civil War. Colt Army and Navy revolvers both employed gain twist rifling. Gain twist rifling, however, is not as simple to produce as uniform rifling, and therefore is more expensive, and seldom used in commercially available products.
Basic idea:
Stand on the freeway and wait for the semi to dust you at 75mph. Hurts like hell and breaks stuff right?
Now stand in the same spot and have him right next to you. You get a bump and then accelerate to the same 75mph. Not nearly so painful.
Sudden accelerations, whether its in rotation or in a linear fashion is hard on stuff. The idea is to softly accelerate the bullets rotation so that things like core/jacket delamination doesn't occur and to help even out some of the chamber pressure. (make it more linear)
Hope this helps.
C.
Stand on the freeway and wait for the semi to dust you at 75mph. Hurts like hell and breaks stuff right?
Now stand in the same spot and have him right next to you. You get a bump and then accelerate to the same 75mph. Not nearly so painful.
Sudden accelerations, whether its in rotation or in a linear fashion is hard on stuff. The idea is to softly accelerate the bullets rotation so that things like core/jacket delamination doesn't occur and to help even out some of the chamber pressure. (make it more linear)
Hope this helps.
C.
Talking about gain twist is like commenting on your best friend's wife's new hair style.....best not say a word, just smile an "I like it!" smile. I am not that smart.
Progressives have been around for a long, long time I have black powder specimens that go back to the mid 1800's (think Pope). Colt used them in their pistols as far back as 1850.
Like the Farmer's Almanac, variable twists can be proven to be the absolutely very best solution in the search for accuracy about every blue moon, with the last major cycle being when Tony Boyer used a Bartlein example back in 2008 to shoot a remarkable .169 GA (something like.03125 gain in twist per inch over the whole length of the barrel) . Everybody that is/was anybody has had a whack at them, Lilja favored the slightest of gains and swore that it provided "grip" on the bullets.....until he didn't think that anymore. In the end he felt that a constant bore....if held constant....did a better job. Bought from him then with it....buy from him now without it. But, that is not the end of it all as many makers still build them.
I own them, shoot them, like them. But.....if somebody had me list out in priority order what I thought held more sway on accuracy, variable gain would be one of the things I would forget to include. Why? Because 100 other things can screw up worse than the slightest of advantageous that MIGHT be had with progressives.
The best part about progressives? The folks that buy them are truly thinking about everything that might be advantageous to accuracy...and how can that be a bad thing?
"What twist is better? I tell guys I don't have that magic book. All I know is the twist has to be fast enough at the muzzle to properly stabilize the bullet when it comes out. "
Frank (barrel maker at Bartlein circa 2008)
Lets say you could control everything....and had one of the best 1000 yard 10 shot groups in the world...did you use a gain twist barrel?
One year later.
http://bulletin.accurateshooter.com...ets-new-ibs-1000-yard-heavy-gun-world-record/
Progressives have been around for a long, long time I have black powder specimens that go back to the mid 1800's (think Pope). Colt used them in their pistols as far back as 1850.
Like the Farmer's Almanac, variable twists can be proven to be the absolutely very best solution in the search for accuracy about every blue moon, with the last major cycle being when Tony Boyer used a Bartlein example back in 2008 to shoot a remarkable .169 GA (something like.03125 gain in twist per inch over the whole length of the barrel) . Everybody that is/was anybody has had a whack at them, Lilja favored the slightest of gains and swore that it provided "grip" on the bullets.....until he didn't think that anymore. In the end he felt that a constant bore....if held constant....did a better job. Bought from him then with it....buy from him now without it. But, that is not the end of it all as many makers still build them.
I own them, shoot them, like them. But.....if somebody had me list out in priority order what I thought held more sway on accuracy, variable gain would be one of the things I would forget to include. Why? Because 100 other things can screw up worse than the slightest of advantageous that MIGHT be had with progressives.
The best part about progressives? The folks that buy them are truly thinking about everything that might be advantageous to accuracy...and how can that be a bad thing?
"What twist is better? I tell guys I don't have that magic book. All I know is the twist has to be fast enough at the muzzle to properly stabilize the bullet when it comes out. "
Frank (barrel maker at Bartlein circa 2008)
Lets say you could control everything....and had one of the best 1000 yard 10 shot groups in the world...did you use a gain twist barrel?
One year later.
http://bulletin.accurateshooter.com...ets-new-ibs-1000-yard-heavy-gun-world-record/
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There is some information on gain twist in the articles on the Lilja barrels page.
Lilja Precision Rifle Barrels - Articles Main Index
In one article he mentions that any decrease in twist is bad for accuracy, gain can be OK.
Somewhere, I cannot find it, but in one, he mentions that Lilja used to do gain twist, but found it did not buy them anything, so they stopped.
Lilja Precision Rifle Barrels - Articles Main Index
In one article he mentions that any decrease in twist is bad for accuracy, gain can be OK.
Somewhere, I cannot find it, but in one, he mentions that Lilja used to do gain twist, but found it did not buy them anything, so they stopped.
I try, but I'm not the submissive type. Hence the flowers at the house last night for the fiance... I have yet to master the phrase, "Yes dear, you're right." and can't bring myself to accept ignorance or the lack of desire to learn as being ok. Would be much easier on me if so.
Thank you for the replies everyone and the clarifications.
