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Carcano 6.5 x 52mm Gain Twist

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8.7K views 3 replies 4 participants last post by  Charley  
#1 ·
To ALL,

The best Gain Twist example I know is the 6.5 x 52mm Carcano.
The Carcano has a Throat Twist of 1:19" which gradually increases rate to 1:8" at the Muzzle.
I'd like to experiment with Gain Twist.

Normal Carcano military ammo is 150gr with 2,400 fps Muzzle velocity.

I've never seen a recovered Carcano bullet, but I imagine the rifling pattern would simply look like a (completely) normal 1:8" Twist pattern. The reason behind Gain Twist is lowered pressure and temperature in the throat area which translates to longer barrel life. Normal, high bore temps should guarantee that a copper jacket continues to-conform-to Local Twist (value) all the way down the bore to the Muzzle.

As best I can tell, the Mod 91 Carcano was built from 1891 thru 1943 with a rear sight normally set to 300 meters and an adjustment range of 600 to 1500 meters. The pre-1939 models have better materials, actions and barrels. The Carcano is (supposedly) quite accurate but, recent Yugoslavian 6.5x52mm (and Norma) ammo is of poor quality, mostly due to undersized bullets (averages 0.2615" diameter) while, Italian military ammo averages 0.2685".

QUESTION:
Does anyone know where to find a good condition (I want to fire it, not collect it) Mod 91 Carcano of pre-1939 vintage?


Bill
 
#3 ·
One of the barrel makers that is used in the benchrest circuits was fooling with gain twist barrels. Can't recall the maker....Kreiger, Pac-Nor, Lilja, Schneider.?....not sure..
Anyway, you might do some looking in the benchrest BB's.
IIRC, the benchresters found no particular advantage to a gain twist barrel.