[320pf]

Scoop,

I check in the Speer reloading manual, they list a twist rate of 1:18.75 for 38 special and 357 mag. pistols. The 38 special loads are all subsonic. The 357 mag in rifle is listed as 1:16. Since all of the pistol bullets are short and fat you can probably use the same rate of twist.

Interestingly, the rate of twist for the 357 maximum is 1:14 in a 14 in barrel. The Speer manual list some heavy (200gr) bullets that are some what longer than the 158 g pistol bullets... but the slowest mv listed is about 1300-1400 fps. So I would guess that you will want a twist rate at lease as fast and the 357 maximum (1:14)... probably more like 1:10 to 1:12.

From the Speer data I calculated that the 200 gr bullet out of a 14 in 1:14 twist barrel 357 Max is doing about 1200 to 1300 rev per sec (rps).

At a MV of about 1000 fps the bullet would spin about 800 to 900 rps. If you increase the twist to about 1:12 the bullet rotation is about 1100 to 1200 rps. If you increase the twsit to 1:10 the bullet will spin at about 1400 rps. This assumes that I did not screw up my math.

I hope this helps

320pf