200 to 300 fps between them out of 7.5" X-frame for same bullet, if you load 325 grain or heavier the the gap gets even larger.

355 grain HC out 454 1550 fps - 460 1980fps both at 57kpsi out of 8" test barrel

Some time back I posted 460 loads velocities for same bullets out of the various barrel lengths.

be safe
Ruggy