Ok, sorry for the delay. I had to dig to find this load, yes I tried it, and yes it gets painful, and IMO it is too much for deer. Hornady 350gr RN over 55.8 grains of 3031 gives 1,900 fps from a 22" barrel. This load zeroed at 100 yards drops 49.7 inches at 300 yards. Zero at 200 yards and you will be 6 inches high at 100, and about 27 inches low at 300. As for black bears, this loads generates 2,803 ft-lb energy at the muzzle, and when it reaches the 300 yard mark the bullet is still moving at aprox 1,000 fps and carrying 924 ft-lb energy.
A cast 405 gr bullet pushed by 51 gr of 3031 makes almost 1,800 fps and generates 2,900 ft-lb at the muzzle, has slowed to aprox 1,050 pfs at 300 yards, and generates 1,005 ft-lb energy. Zeroed at 100 yards it will drop 52 inches at 300 yards. Zeroed at 200 yards it will be 7 inches high at 100, and 30.5 inches at 300 yards.
The 45-70 is capable of hitting targets at 1,000 yards and beyond, but shooting game I strongly recommend shots be limited to 150 yards or less.