myroman,
i am sure your load will work fine. i have shot many of them with 45, 454,
500 linebaugh. the most often used load has been a 310 keith cast of w/w and shot out of a ruger 45 colt. velocity has been around 1200fps. on body shots, we get an exit if no shoulder bones are hit.
bison are some of the toughest animals i have seen. hits in the body with big rifles sometimes go unnoticed. yet i have seen many die quickly with properly placed lung shots from a 45 colt. they are built differently than other animals. probably the biggest mistake people make when shooting them is to hit too low and too far back in combination. that results in a hit to the stomach. one of the most effective shots i have seen for bowhunters is high behind the shoulder and from behind angling in. that way they hit more lung and dont have the shoulder to stop the arrow. on a perfectly broad side shot, the best seems to be as close to the shoulder as you can get (know where the bone is) and from 1/3 to 1/2 the way up. you will still have to penetrate alot of shoulder muscle but not the bone. the heart is partailly covered by the shoulder. if you go too far forward, ahead of the shoulder, remember that the lung cavity tapers out quickly to the front. not much will be hit. if this sounds contradicting, just picture the lungs as a steep tapering cavity with the biggest mass to the rear of the shoulder blade. the greatest mass is relatively high. the stomach comes forward below that. the heart is most reachable from slightly behind the shoulder and about 1/3 way up. its my favorite shot and it damages the top of heart and the major vessels. they seem to leak faster than the lungs. my second favorite is the before mentioned high and angling in behind the shoulder blade. that shot will damage rib steaks though. we will shoot 2 more tomorrow. sounds like the hunter is using a 405 win. hope this helps. Jeff