Gain Twist Rifling

[TATER]

I was looking at the 460 S&W revolver and noticed that it had "Gain Twist Rifling". I looked up what this was and it seems that some if not most people have come to say that there isn't any benefit to accuracy. Do you guys think this is of any use in a revolver? I think the concept is sound, but is this just a marketing ploy?

[versifier]

The idea is not a new one, and it has had different names over more than a century. It started out IIRC in very expensive double rifles for dangerous African game. I do not believe that it has any real effect on accuracy, especially in the short barrel of a handgun. Even if it does, there aren't many handgunners who are up to the level where they could notice it without a Ransom Rest, especially in a handful like the .460. I may be wrong (and I have not had a pair of revolver with and without to play with) but I think it's just a marketing ploy, or a status symbol for those who talk more than they shoot.

[TATER]

Thanks versifer for the input. After reading all I could find, it sort of makes some sense in the 17 and 460 S&W with the rapid acceleration of these two rounds and I guess it wouldn't hurt. From what I've read it will help the forcing cone survive longer. Just looking at it from a layman's point of view, you'd think all barrels would have this method of rifling. I don't plan on getting a 460, was just wondering about "Gain Twist". And you are probably right about it not really helping much in accuracy in a handgun like the S&W 460.

[runfiverun]

they mainly do it so the bullet will engage the rifling otherwise it would strip and there would be no accuracy.
it also helps to maintian the rounds velocity as when the bullet starts turning it wastes forward speed to spin it.

[versifier]

The theory has always sounded plausible, and it has sound roots. Wasn't it called "Paradox" rifling in the old double m/l elephant guns? It started about half way up the barrel and imparted some spin and stability to a conical bullet as compared to the older smooth bores. (That evolved into today's screw-in rifled choke tubes for shotgun slugs.) In cartridge rifles the twist started slow and speeded up as the bullet approached the muzzle so the huge heavy slugs wouldn't strip out. It made sense with a big soft lead slug, but I don't see that it makes much sense with a jacketed bullet. Maybe it does. One obvious problem is the difficulty in machining it. It's hard enough to make a good rifled barrel without having the twist rate change constantly along its length.

Sometimes a logical assumption applied to firearms doesn't hold up under actual testing, and sometimes the most bone-headed idea works out great. Rifling itself was a bone-headed idea at one point that happened to work out. The original idea was to give the black powder fouling a place to accumulate so you could get more shots before cleaning, and then they got the idea to cut it in a spiral to increase the number of shots even more. In testing, it was soon noticed that the rifled barrels were much more accurate out to longer ranges. Hmmm. Where would we be today without it?

[runfiverun]

versifier thats almost exactly the way the designers at s&w explained it to me.
the italian carcano also uses a gain twist rifling,beware these if the bbls have been cut down.
even in a regular rifled bbl say a 10 twist if you cut the bbl back to say 18"s the velocity drops enough that it acts more like a 12 twist as the bullet hasn't accelerated enough to fully gain the forward rate to make the rpm numbers come out right.
i don't fully understand it enough to explain it , but i have a grasp of how it works.

[Echo]

I believe the Paradox guns were made with rifling in just the last few inches (and I mean the last 2 or 3 inches!)of the barrel, and the rifling acted like a choke for the shotshells that could be fired through the gun.

[versifier]

From what I have read, Paradox rifled barrels performed horribly with shot - remember they were mostly muzzle loaders and the plastic shot cup that might have made it workable was more than 50 years in the future. The two I have seen were 6 and 8 gauge double rifles with percussion cap ignitions. I cannot remember who made them, but they were Brittish, nicely engraved, and cost enough (over $40K) that I was very nervous handling them despite my curiosity. Being m/l's, the breeches didn't open so I could not see how far down the rifling went, but it was obvious at the muzzle and the owner said they went down about halfway. (This was at odds with what I had read also, Echo, but I took him at his word. It may well be since they were custom made-to-order rifles that it varied with the buyer's preference and/or possibly from maker to maker, but that is purely speculation on my part.) He also said that the recoil from them was "brutal", even though they weighed fifteen to twenty pounds (my estimate). His opinion was that one would be better off in front of one that was being fired - that way the pain would end much sooner. He said he had fired one shot out of the 8 with a round ball over "a modest bp charge" and that was enough for him, then added that you couldn't pay him enough to fire the 6. I certainly wasn't even tempted, though they were beautiful.

[ancestor]

In the book African Rifles and Cartridges ;John Taylor, p90-91 describes the paradox and using same. He notes that the rifled section is in the area where the choke would normally be.