theres nothing walking in north America that a properly placed 175 grain bullet from a 7mm rem mag launched at 2900fps won,t kill 100% dead with a single hit out to well past 500 yards
ive loaded 150 grain speer bullets in a 270 win that were launched at 2900fps to kill elk,Ive used a 200 grain speer 30 caliber from a 30/06 leaving the muzzle at only 2550 fps to kill elk out at 400 plus yards, and loaded that ammo for others, we have all had excellent results.
think about it a second even with that bullet in that load you used to use leaving the muzzle at 3100 fps, that bullet was down to near 2900fps by the 100 yard mark, most elk are killed at well under 400 yards, Id doubt it if more than 20% were killed out past 300 yards, I know Ive certainly spent 43 years hunting elk and had very few shots that were taken at over 300 yards, simply because Ive rarely seen elk in the open, while hunting, and shots in the timber and canyons rarely exceed 300 yards... BTW 1885 is a really nice rifle, Ive got a similar B78 re barreled in 300 weatherby
http://www.hornady.com/ballistics-resource/ballistics-calculator