General discussion > Black Powder Shooting

Gain Twist

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Tim May:
Gain Twist rifling is it good for
shooting round ball or conical
bullets ? Any experience pros
or cons ?
Tim

Fyrstyk:
I have gain twist in two .58 caliber guns that I only shoot roundball with.  I can't say for sure that it is better than a regular twist, but the accuracy of both barrels is outstanding.

Bob Roller:
I know that with round balls and the short bullet called the Pickett "ball" work well with a gain twist.
Rifles made by Harry Pope did their best when used as a muzzle loader and his barrels had a slight
gain and they used a long bullet that was lubricated,usually about 32 caliber.
Bob Roller

Carl Young:
Bartlein barrels https://www.bartleinbarrels.com/barrel-faq:
I’ll quote what Pope (Pope was one of the greatest barrel makers from a bygone era. His barrels along with Schalk who he learned from and gives credit to and Schoyen, and Zischang made barrels for the Schutzenfest type of guns/shooting in the late 1800’s to early 1900’s) said around a 100 years ago first. “The advantages of the gain twists are three. 1st The twist being less at the breech, gives less friction to the bullet; it therefore starts easier and quicker, giving the powder less time to burn on in front of the chamber, which therefore fouls less than in a barrel of uniform twist at the same necessary muzzle pitch (twist). 2nd The slight change in angle of the rifling, in connection with choke bore (lapping choke bore of the barrel), effectually shuts off any gas escape of gas and prevents gas cutting, which is another case of imperfect delivery. 3rd It holds a muzzle loaded bullet in position much better than a uniform twist…

Now I (Bartlein) will add some more to this. First off I feel this applies more to a lead bullet shooter ... With a gain twist barrel the bullet cannot go to sleep. The rifling is always putting a fresh bite on the bullet as it goes down the bore of the barrel. This is why I always go back to a cut barrel being better than a button barrel. A cut barrel even with a straight twist is more uniform and consistent than a button barrel. With button rifling the button can hit a hard spot/soft spot in the steel and it will slow the button down. The button could speed back up and do the twist it’s suppose to be doing but either way you end up with a non uniform twist and it the twist keeps getting slower towards the muzzle. These two things are a accuracy killers and lead to consistency problems/fliers etc… I feel even a slight gain twist will help accuracy wise... For the most part I would say there is no velocity gain in a gain twist barrel with the same load. What has been conveyed to us and it goes back to Popes 1st point is that shooters have noticed that they can run a slightly heavier powder charge vs. a shooter with a straight twist barrel. As the bullet is starting easier into the rifling my only guess is the pressure isn’t spiking as fast or is delaying the pressure curve. Hence forth they can get more velocity out of the gain twist barrel. I feel pressure is pressure and that the twist doesn’t have anything to do with pressure for the most part but my only guess is that the gain twist like I said earlier is delaying the pressure curve...

If you want to go further get a copy of The Story of Pope's Barrels by Ray M Smith

Dphariss:
The gain twists seems to have come about with the Picket bullet. It was more twist sensitive than the RB and some pretty aggressive gains were used 1:48 to 1:30 to 1:36. A picket is pretty short and has a very short driving band and will shoot in such a twist.
Harry Pope’s comments on sealing the bore are probably not quite correct unless VERY hard bullets were used OR smokeless powder, remembering that Pope was making barrels well into the 20th c. BP has an amazing ability to make and undersized bullet fit the bore with no gas cutting. Bullets .010” under groove will shoot fine with BP. So long as the design prevents nose slump.
For a bullet barrel, based on what I have been told by a guy who has experience in the making of gain twist barrels, I would not use more than 1/2” gain. Such as starting at 16 and ending at 15 1/2. This stops any possibility of the twist slowing at the muzzle. This BTW could have been the reason the gain came into use in the first place. This could easily have been a problem with a wooden, shop made guide. Something the RB would not care about but would likely be troublesome with a picket.
 I think all the Colt percussion revolvers had a gain.
And Bartlein knows gains and I would defer to him in anything I have posted here.

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