Mbogo,

Don't take my initial critique so personally. No one would be jumping on you (or rather your associate) had you not stated that the bullet was "3 inches beneath the skin" as though it, in fact, was recovered there. The reality is this would only happen if the powder charge was planned to be horribly insufficient. My guess, since you now say that the bullet was not recovered "3 inches beneath the skin" is that the bullet reached the vitals (or better) and you would have had a dead bison had you been patient! No need to turn a majestic animal into swiss cheese! I have shot truly wild bison in the vitals with my .416 (twice in fact) and had them just stand there! Unless you hit a bison in the CNS or at just the right time through the heart (read Robertson's theory on this in The Perfect Shot), he will NOT just fall over. He MAY trot away or, more likely I think, just stand there and slowly bleed out.

Best,

JohnTheGreek