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progressive rifleing
fitzhugh
Member Posts: 7 ✭✭
Has anyone ever experimented with progressive or increasing rifleing?I am talking about starting out at zero to minor twist at the chamber and increasing it until at the muzzle. Start at 60 to 1 and end at what ever is needed. I would think that with high vel./ heavy bullit rounds the transition would help to keep the pressures down. Sort of easing the bullit into it as it were.
Comments
S40
Harry Pope did it for scheutzen rifle barrels.
As S40 said, the Italians did it for the Carcano.
Smith & Wesson does it for the .460 monster magnum.
Some target rifle barrel makers are using a tiny amount of gain twist, from say 16.25" to 16.0" for a .22 lr to be sure the rifling is "tight" on the bullet.
Bartlein will make any progression you like, you could probably even get the old Metford design with three different twists over the length of the barrel with fairly sharp transitions.
The Paradox mentioned below is not really related.
The rifling in those I have seen does not "develop gradually" it is very distinct for about two inches right at the muzzle with a rather short leade from the main smooth bore. The main advantages of the Paradox were that it weighed a lot less than a fully rifled gun of the same bore and that it would give about improved cylinder patterns with shot. One of the cutest guns I have seen was a Westley Richards 20 bore Faunetta, suitable for medium game.
Know what you are referring to and know that others here are knowledgeable of "progressive rifling", gain twist, etc. I'm not an expert on it, but I'm sure one or more will come on and give you the info you are interested in finding.
Good seeing you. Good luck to you.
Its used on artillery pieces, as one example.
As mentioned, it used to be used on old percussion revolvers and a very modern gun to use it is the Smith .460 revolver.
It doesn't alter the chamber pressures, but the idea of slowly easing the spin of the bullet is correct.
The idea is that when a fired bullet smacks the rifling, its going to spin. If the bullet is really heavy and hits the rifling hard, not only is the rifling going to spin the bullet, but due to Newtons second law (action/reaction) the bullet is going to spin the rifling!
The gain twist eases the stress on both the bullet and the gun.
Without the gain twist (for example) not only would the .460 revolver kick backwards hard on recoil, but the impact of the bullet against the rifling would also tend to twist the gun along the axis of the bore during recoil!
Emmett
No, I goofed up here. The grooves in the bullet at the breech are parallel to the sides of the bullet. When they reach the end of the barrel they are wider than they were at the breach. The lands will be narrower.