Progressive Rifling

[Archer 756]

Looking for comments on progressive rifling.

 

[Pete G]

Seems to work OK, but no better than standard rifling.

 

[Nobade]

As in depth or twist rate?

 

[Rifleman1776]

Seems to work OK, but no better than standard rifling.

That is my understanding also based on what I have heard from others and have read. I believe if it gave superior accuracy we would see it used almost exclusively in rifles.

 

[Rock Home Isle]

Is “progressive rifling” the same as “gain twist rifling”?

In “gain twist rifling” the twist of the rifling gets faster and faster as the projectile approaches the muzzle. For example a 1:66 twist at the breech, could be accelerated to a 1:35 twist at the muzzle. “Gain Twist Rifling” allows a gun to be very accurate with an incredibly wide range of projectiles, from rounds balls, up through conicals and into long range jacketed projectiles.

 

[LME]

That is my understanding also based on what I have heard from others and have read. I believe if it gave superior accuracy we would see it used almost exclusively in rifles.

I don't know much about progressive rifling but what I do know is when the bullet starts in a slow twist and the twist tighten as it goes It down the barrel it has to cut new groove in the bullet. I can't see how it is an improvement? It apears to me in my simple mind that it might hurt accuracy?

 

[William Lincoln]

The Remington New Model Army' (1858) came with progressive rifling in
some series. The Pietta Shooters model featured it as well. Pedersoli has
it in its fine Revolver version (at a steep price) I think that
it would help a little with accuracy---but not as much as the skill of
the shooter. Witness Championships won by largely standard rifling.
I do not think the Old Army by Ruger was progressive-- and it is a
top contender.

 

[hanshi]

I have one rifle with a gain twist bore. I bought it over 55 years ago and it's a .45 underhammer. Accurate? That's an understatement, the thing is phenomenal. I can't say it's more accurate than any other rifle I've owned because one would have to be a much better shot than I am in order to tell.
This target is typical of what it can so. Some targets are better and a few are not as good. The flyer was my fault and called.

 

[maillemaker]

There are two kinds of progressive rifling. Progressive depth, and gain twist. Progressive depth was discovered when they were rifling smoothbore guns that did not have a lot of material near the muzzle. So, they reduced the depth of cut near the muzzle. This was discovered to improve accuracy.

 

[Archer 756]

Note! Looked up more info on this subject and found out that almost all of top shooters for NSSA shot progressive arms. This type of rifling was also used in War Between States by snipers.

 

[Old Hawkeye]

I don't know much about progressive rifling but what I do know is when the bullet starts in a slow twist and the twist tighten as it goes It down the barrel it has to cut new groove in the bullet. I can't see how it is an improvement? It apears to me in my simple mind that it might hurt accuracy?

You are confusing gain twist with progressive depth twist. Two different animals. In a gain twist the bullet doesn't "cut a new grove" it just follows the rifling twist as it gets faster. In a progressive twist rifle the twist is constant, but the depth of the rifling gets shallower as the bullet gets closer to the muzzle.

 

[Rod Man]

Note! Looked up more info on this subject and found out that almost all of top shooters for NSSA shot progressive arms. This type of rifling was also used in War Between States by snipers.

Ned Roberts book ,"The Muzzle-loading Cap Lock Rifle" talks about it. I tell ya, those fellas had there stuff together.

RM

 

[11Bravo]

I had a progressive depth barrel made in the 70s by H&H barrel works for my 58 underhammer. The barrel worked great for the heavy minis I shot. As far as I know my original Colt revolvers came with gain twist barrels.

 

[FlinterNick]

From my understanding, Progressive depth rifling was used with guns that had tapered barrels, which the thickness and integrity of the barrel would not have been compromised due to the rifling.

There was an 1816 musket conversion project where barrels that were converted to rifled muskets used progressive depth rifling, this procedure was also practiced on the models 1835 and 1840 flintlock muskets (converted to percussion). The French also had practiced on many of their charleville muskets as the french commonly made their barrels slightly heavier in the breech and middle than most other military arms.

 

[LME]

You are confusing gain twist with progressive depth twist. Two different animals. In a gain twist the bullet doesn't "cut a new grove" it just follows the rifling twist as it gets faster. In a progressive twist rifle the twist is constant, but the depth of the rifling gets shallower as the bullet gets closer to the muzzle.

I still don't understand? If it starts in a slow twist and the twist gets faster it looks like to me it can't follow the slow grooves? It may widen the grooves as it travels down the barrel but then it couldn't seal the gasses completely? On our fighter jets the guns use a progressive twist so there must be something going on that no one has yet explained?

 

[Nobody85]

The grooves are still the same distance apart. They just have more rotations given the same length of barrel. Think of a train on a track. The track might have a turn that progressively gets tighter, but the track is still the same width.

 

[dave951]

Once again- there is Progressive rifling and that refers to the DEPTH of the grooves. Gain twist refers to the rifling twist getting faster as it goes to the muzzle. They are as different as night and day. Progressive depth rifling is the ticket with minies. Gain twist is more for bullets. Gain twist also suffers from having a very small window for accuracy using bullet weight and velocity. Stay in the sweet spot and it can be a wonderful thing. Stray but a little and it goes pear shaped really fast.

 

[Ninering62]

The grooves are still the same distance apart. They just have more rotations given the same length of barrel. Think of a train on a track. The track might have a turn that progressively gets tighter, but the track is still the same width.

Exactly, good explanation.

 

[waksupi]

Harry Pope experimented with gain twist rifling a lot. He determined he could see no advantage in accuracy over straight twist rifling. The caveat is, he was shooting elongated projectiles, rather than round ball. From my experience with gain twist, same holds true for round ball.

 

[dave951]

Harry Pope experimented with gain twist rifling a lot. He determined he could see no advantage in accuracy over straight twist rifling. The caveat is, he was shooting elongated projectiles, rather than round ball. From my experience with gain twist, same holds true for round ball.

It also works with some conicals. The key is the length to caliber. A round ball is almost exactly 1:1. Some short conicals are in that area too. A round ball theoretically contacts the bore only at the tangent point of the circumference.

My theory on long bullets not working in gain twist is the front of the bullet is being twisted faster than the rear putting a torque effect on the bullet and causing either the nose or base to jump the rifling.