Kind of jumping ahead here to get my 2 cents in, A Rossi 92 short rifle in 45 Colt will run a 300 gr XTP at 1700 FPS which will/would probably give a grizzly bear second thoughts about is future behavior. A 300 gr to 325gr hard cast would probably shoot thru the same grizzly end for end. A 250gr bullet at over 1800FPS will reach 150yd easily and a 0.452" hole thru a whitetail will leave a short blood trail. My Rossi weighs almost exactly 5# and as been fitted witha shotgun style stock. A 5# rifle running the 300gr gives a stiff little kick with 300 gr. Recoil with a 454 tends to move the magazine tube forward. Also with appropriate pressures a 45C will exceed a 44 magnum by about 10% in kinetic energy.
What load you using to get that? The highest estimates I've calculated in quickload were around 1800 FPS with a 200 grain bullet before running out of powder space, much less a 300!
