gain twist rifling

[ramrod]

hello all . can someone please explain the benifit of gain twist rifling . am curious , i hear it mentioned in muzzelblasts and other places .

[Standing Bear]

You can use heavy loads and bullets without stripping the rifling during the slow twist rate and then get the RPMs up with the faster twist at the end. Don't know that it is applicable in shooting roundballs unless with shallow grooves.
TC

[Dphariss]

The bullet/ball needs to be at a constant rate of spin at the muzzle or the twist rate needs to be increasing at that point. If not accuracy may suffer.
With elongated projectiles like the picket bullet this is more important.
In my opinion the gain grew from this. OR it came from the pickets stripping easier than the round ball. The more rotational inertia a projectile has the more likely it is to damage the patch. Starting with a 72" twist and ending with a 36 might prevent this with the picket or a RB. Note that the cloth patched picket bullet was never more than about 2 calibers long and had a bearing surface similar to the RB.
However, bullets with long bearing surfaces do not tend to do well with 2:1 gains. Modern gain twists for elongated projectiles feature relatively little gain compared to the old RB and Picket bullet twists.

Dan

[hanshi]

I really can't say what, if any, benefits gain twist rifling has over any others.  I can say that the most accurate barrel I own is a .45 gain twist in a round ball rifle.

[smylee grouch]

I think Numrich Arms used to sell a gain twist barrel in 45 cal.  One of my shooting partners had one and as I recall it was a fairly good shooter but I wonder if it wasnt also kinda fussy with powder charges. Quite a number of years ago so cant say for sure. Maybe others here have had that experience too.

[JCKelly]

Gain twist has been invented, or at least made popular, several different times. Spiller & Burr used it in the 1860's for their .36 cal revolver. In our time the Italian Carcano carbine of ill repute used gain twist. Various modern semi-auto 9mm & .45 cal barrels use gain twist.

Maybe you like it, maybe not. But someone else will, I suspect, in the future.

[Paul Griffith]

IMHO, if  it was better than uniform twist with a round ball we'd all be making and/or using it. For the machinist making the barrels it's not much to set up for.

Paul