Well guys I have been loading for the 10mm since 1987 and have come up with some awesome velocities.
Thanks to Mike Mcnett of Double Tap ammo for posting reload data I now use IMR800X powder for my top 10mm loads.
In my 4.6" G20 I get 1650fps & my 6" Colt D/E I get 1850fps with Nosler 135gr JHP's.
I get 1300fps in the G20 and 1495fps in my D/E with 190gr Sierra FPJ bullets.
Compare that to your 357 velocities........ :shock:
Shorter barrels, heavier bullets, not 6 but 10 to 17 rounds in the gun depending on which mags you have.