Variable Twist Rifling

[LJH]

I remember reading about variable twist rifles in the 80’s; I found it to be a very interesting idea. The word of the day was that you would achieve more velocity, less pressure, and better accuracy.
Did this technology never matured? Or possibly no real benefit was to be had and it was all hype. Did anyone actually own a variable twist and if so how did\do you like it?

 

[rcmodel]

Gain twist rifling has been in use since black powder Kentucky rifle days.
The Italians used it on the Carcano rifle in the early 20th century.
The military used it on cannons.
S&W is using it now in the .460 revolver, and maybe the .500.

It may have some real advantages on common sporting calibers, but whatever they might be has not proven benificial enough to make it mainstream so far after a couple hundred years.

rc

 

[NCsmitty]

It's usually called gain twist rifling and has been used in some military rifles like the Italian Carcano.
Here's some other explanations on the subject.

http://en.wikipedia.org/wiki/Rifling


NCsmitty

 

[RSVP2RIP]

I understand that some of the original Colt percussion revolvers such as the 1860 used it. The Mowery Rifle (muzzleloader) was availible in it. As I understand, the effects weren't justified by the increase in production costs. But that was in a time before CNC machining centers.

 

[jmorris]

I have an SVI pistol with Schuemann AET (gain twist) barrels in 9mm and 45 acp. http://www.schuemann.com/default.aspx It's the most accurate self loading pistol I own, the factory test targets are from 50 yards.

 

[danweasel]

I know it was tried in pre/early WWII anti-tank guns. It was used in conjunction with a barrel that actually got skinnier towards the muzzle. This was to try to produce small caliber projectiles that could defeat the thin armor of the time. But it didn't pan out, obviously.