Progressive twist rate?

[vern faulkner]

After reading all the threads concerning slow/fast twist rates, I got this idea :hmm:. Was there ever a rifled barrel made with a progressive rate of twist (starting out slow and progressively speeding up)? Would there be any advantage/disadvantage to this? It may be a dumb question, but no where in my profile is it stated that was very smart :shocked2:.
Vern

 

[Bill Hall]

Yep, it's called a gain twist. I've heard it puts a maximum rpm on a projectile, but not all at once. The bullet builds up a faster spin as it builds up speed going down the barrel. I know gain twists were popular back at the Creedmore target range in the 1800"s. Bill.

 

[Bill Hall]

P.S. If you get the chance to read The Muzzleloading Caplock Rifle, by Ned Roberts, he writes about the gain twist quite extensively. Bill

 

[dyemaker]

The London Armoury Kerr volunteer target rifle had gain twist.

 

[ohio ramrod]

Gain twist was and still is popular with long range shooters since it allows the projectile to be spun at a faster rate leaving the barrel with less force required to obtain the spin since the projectile is accelerated at a steady rate over the length of the barrel.If the old memorory is correct, There was an article in muzzle blasts about six years or so about the torques involved and they concluded that for a patched round ball there was no significant advantage in gain twist.

 

[paulvallandigham]

The late Harry Pope, who made famous target barrels, guns, and set records with BP rifles, but MLers, and early Breechloaders, popularized the use of Gain Twist.

The first, and I BELIEVE, only country to adopt the Gain twist in a military issue rifle was Italy, when it brought out the 6.5 x 54 mm. Carcano, Bolt Action rifle in 1891. Jacketed bullets, made of Steel, were used in these early rifles. In 1936, the Italian government modified the rifle and brought out the carbine version, using standard twist rifling. Most of the older rifles had their barrels replaced with standard rifling.

One of the questions concerning the rifle used to assassinate President John F. Kennedy in 1963 is whether its barrel had the "gain twist" rifling, or standard "straight" twist of the later modifications. The gun is in the National Archives, or Smithsonian Museum, in Washington, and the curators won't allow an inspection of the bore to determine the answer to that question. The ammo used was modern Winchester made commercial ammo- not war surplus ammo often sold with the guns. The jacket on the bullets were thin copper, similar to what you find in any copper jacketed bullet today. The issue is why the third round began to spin once it penetrated the President's head, leaving a huge exit wound, and blowing up, leaving traces of lead in the brain, and two pieces of lead that hit the chrome trim above the visor in front of the driver's seat, and the inside of the windshield in front of the driver. Two pieces of lead were found on the floor under the driver's feet, one weighing about 22 grains, and the second weighing about 44 grains. ( Warren Commission Report) None of the copper jacket was found or recovered. [lesson: If you don't know what you are looking for, you are rarely going to find it!]

More recent testing has shown that Gain twist does not produce substantially better accuracy in high velocity target rifles. Because of the time and expense needed to produce gain twist rifling in barrels, its rarely done today. The idea is explored by target shooters every generation or so, with the BP cartridge silhouette shooters being the last I have heard of seeing if they can get better accuracy with cast, lead bullets using Harry Pope's designs, and gain twist rifling.

You can find information about this from the Cast Bullet Association, and in the Single Shot Exchange magazine. For MLers, the Slug Gun shooters, who shoot long bullets out to far distances are the guys to talk to about gain twist. They have exhaustively tested this concept and found it not worth the expense and effort. [ I asked!] :surrender: :hmm: :thumbsup:

I suspect that our own IdahoRon has either tried gain twist rifling with his paper-patched bullets, or can tell you why its not worth the bother. :thumbsup:

 

[Bearbait2]

Mr. Ancient One,
Our .58cal Parker Hale 3-Band Enfield has gain twist rifling.
Best Wishes

 

[dyemaker]

While searching online I came up with this but have no idea... I saw that Smith and Wesson has used gain twist. There was also a theory being that there is less stress on bullet and barrel from torque as the bullet engages in gain twist rifling. Sometimes barrelmakers increase twist rate slightly at the muzzle just because any reduction in twist rate has negative effects. Also Colraine barrels give their two cents here. I dont particularly like them because I believe their twist rates for roundballs are too fast. Personally, I tend to agree that it is not worth the expense or effort for roundballs at least judging from past threads I've read elsewhere.

Link

 

[Zonie]

I think it was Orion Barrel Co (J. Cunningham) that offered gain twist barrels for muzzleloaders quite a few years ago.

I haven't seen any of their ads for a long time so I suspect he is out of business.

 

[ResearchPress]

Our .58cal Parker Hale 3-Band Enfield has gain twist rifling.

I think you are confusing gain twist rifling with progressive depth rifling. The Parker-Hales were manufactured with the latter, as were the originals. The depth of rifling decreases from breech to muzzle with progressive depth rifling of the P/53, but the rate of twist remains uniform. With gain twist rifling the rate of twist increases from breech to muzzle.

David

 

[hanshi]

My H&A Heritage Model underhammer has the gain twist rifling. I specified gain twist when I ordered it back in the mid 60s. The rifle is extremely accurate but I don't know if/what roll the gain twist plays in said accuracy.

 

[Tumblernotch]

Our .58cal Parker Hale 3-Band Enfield has gain twist rifling.

I think you are confusing gain twist rifling with progressive depth rifling. The Parker-Hales were manufactured with the latter, as were the originals. The depth of rifling decreases from breech to muzzle with progressive depth rifling of the P/53, but the rate of twist remains uniform. With gain twist rifling the rate of twist increases from breech to muzzle.

David

That's what I was getting ready to say. I'm not aware of any original production rifle-musket with gain twist. I do know that the US Ordnance Office included gain twist barrels in the tests run to determine the best barrel for the new rifles and rifle-muskets in 1854. They figured somehow that by using gain twist they would increase drift and reduce deviations. But, they found that as these barrels fouled, the bullets stripped out by the time they reached the muzzle. They decided on a uniform twist with progressive depth rifling. A British report, by Lt. Col. Gordon mentions gain twist used in Lancaster's rifle with elliptical rifling and concluded that it tended to deform the bullet. I have read in another report (can't remember the source) that the Americans found that a hollow based elongated ball was deformed badly by gain twist, the soft lead having to change its shape rapidly on its passage through the barrel. I'd have to agree with that. I'm no ballistics expert, but picturing a soft lead projectile staying fixed on a spiral path of shallow grooves that are turning more rapidly as they progress toward the muzzle at nearly 1000 fps is hard to believe. Add the fact that those grooves will soon be partially filled with fouling and lead, making it even harder for the bullet to stay in the grooves. The only thing that I can see that would offset this to any degree would be if progressive depth rifling be used in conjunction with gain twist. Then the increasing pressure around the ball would possibly force the bullet to stay in the grooves. That of course would rely on the bullet having as little windage as possible with no dents or other damage to the skirt allowing gas to blow by. And even then, you will still have some deformation to the ball by passing through constantly changing rifling. As for windage, the standard was .005 inch for the US Burton style Minie. I find from the British report that .009 inch windage was used, but have to remember that the ball was used wrapped in its cartridge paper.

From what little knowledge I have of gain twist, it seems that it works best with jacketed bullets in modern firearms. From what I have read about those early tests, it seems that it may have worked with soft lead in some barrels firing round balls and picket balls where bullet to bore contact was minimal and less likely to deform the bullet.

 

[cgg]

The Colerain barrel company talks about gain-twist barrels on their website and they make a 42" barrel that "gains" from 1:96" at the breech to 1:48" at the muzzle.

Another Pennsylvania barrel maker, Bob Hoyt, is a gain-twist fan too, I think, but I have not heard that from him directly. Might be worth asking him though if you are interested.

 

[pargent]

i thought colts cap & ball revolvers (some of them ) had gain twist rifling ????

 

[ResearchPress]

The War Office (GB) Report on Army Rifles published in 1863 gave Enfield, Whitworth, Lancaster (all muzzle loaders) and Westley Richards (capping breech loader) rifles.

The Lancaster was oval bore and gain twist, the spiral at the breech being 1 in 36 and increasing to 1 in 33 at the muzzle. Bore: major axis .580, minor .572. This was trialled against the Enfield with twist rates of 1 in 78, 1 in 63 and 1 in 48. The Lancaster was more accurate when clean and fouled, accumulated less fouling and was more easily cleaned. When the small bore (.451) rifles were trialled the Whitworth was the more accurate.

William Metford's gain twist barrel was used famously on the Gibbs-Metford long range muzzle loading match rifle and also on later breech loaders in both military an match rifle configurations by both. His barrels dominated in target shooting from the 1860s to the close of the black powder era in the early 1890s. His military breech loaders were particularly successful. Metfords 2000 yard rifle from 1865/66 had gain twist rifling finishing with a pitch of 1 in 13.

Sir Henry Halford noted that the slower the pitch the less the barrel fouled and that a quicker rotation could be given to a bullet with less fouling at the breech than with an even pitch.

Another feature of gain twist rifling is that it shears the paper of a paper patched bullet nicely such that the paper easily falls away as the bullet exits the barrel.

All that being said in long range match rifle shooting rifles with uniform pitch seem to have given equal results to that of gain twist.

David

 

[Trench]

After reading all the threads concerning slow/fast twist rates, I got this idea :hmm:. Was there ever a rifled barrel made with a progressive rate of twist (starting out slow and progressively speeding up)? Would there be any advantage/disadvantage to this? It may be a dumb question, but no where in my profile is it stated that was very smart :shocked2:.
Vern

Just when you think you came up with a capital idea, you find out someone already did it over 100 years ago. However, at least you know your mind is on the same track as the genius you thought it up in the first place. :grin:

 

[dyemaker]

This is where I read about the Kerr rifle. It was used by Confederate sharpshooters during the civil war. Link Notes on Rifle Shooting by Captain Heaton

 

[zimmerstutzen]

Harry Pope used gain twists with black powder but found that it was dangerous with smokeless. Different styles of rifling,different twists, different depths, widths and shapes have pretty much all been tried over the years with most of the experimenting being accomplished back in the first two thirds of the 1800's. Harry Pope was one of the later greats. I think his system of rifling was about as close to genious as it gets.

 

[Bearbait2]

Mr. Minshall,
No, I am not confusing the two but apparently I am mistaken as to which our rifle has.
Thank you for setting the record straight.
Best Wishes