Ok, I've been pondering this for a while now. My wife has drawn a cow tag that she has a good chance of filling. I scouted out the area and she is going to have to be proficient at shots up to 500 yards. My question is should I go down in bullet weight to cut down in recoil for practice or go up in weight for more energy and less practice (kind of recoil sensitive). What bullet should I use granted the slower muzzle velocity from a 20" barrel?