With the rifle the velocity will increase over the standard handgun round.
a 1200 FPS 240 grain jacketed bullet out of a 6" handgun will be above 1500 or higher.
Hotter loads may not be needed to shoot deer or other similar game at short range. (10 -75 yards)
You can also go to the lighter 180 grain loads that start out in a handgun around 1600 FPS and will be almot 2,000 FPS out of a rifle.
a 16- 20" arrel will maximise your velocity.