If you are going to rechamber a 45-70 the gun will have to be re-regulated. I have a Chapuis 45-70 that has been regulated to shoot a 400 grain bullet at 1800 FPS. With the proper bullet I think this gun is adequate for any soft skinned game on this planet. Also, I don't think I would want to shoot a 450 nitro in this eight pound gun.

Dave