Provided you had "HEAVY" ammo , such as what's available from Buffalo Bore, and the shooter is capeable it would be effective out to about 300 yards.

Buffal Bore has a 44+P+ load that fires a 340 grain bullet at 1478 fps out of a 7.5" barrel but is suitable in only certain firearms (Ruger redhawk, Taurus raging bull, Dan Wesson) Others are plenty strong but BB says that their cylinders are too short for the long 340 grain bullet.

http://buffalobore.com/ammunition/default.htm#44P

However, most people consider it about a 100 yard range gun at best with regular ole ammo.

To put it into perspective as to how powerful this load it. The Federal 300 grain load would have 1000 foot pounds at 170 yards. THe Buffalo Bore load would carry 1000 foot pounds all the way out to 270 yards.