against a hostile and a buffalo size game:
First off, I am going to assume you mean Cape Buffalo or Water Buffalo and not bison. Bison fall down pretty easy and are not known for being overtly aggressive.
7x57 mauser- 600 yds against a hostile, 100 yds max against a buffalo to give you enough penetration to try to make it through the internal organs.
7mm rem mag- 1000 yds against a hostile, 200 yds max against a buffalo
.308 win- 800 yds against a hostile, 100 yds max against a buffalo
.243 win- 700 yds against a hostile, don't even think about using it against a buffalo
.270 win- 800 yds against a hostile, 100 yds max against a buffalo
30-06- 1000 yds against a hostile, 200 yds max against a buffalo
8mm mauser- with European style loads, 1000 yds against a hostile, 200 yds max against a buffalo
9mm mauser- 500 yds max against a hostile, 150 yds against a buffalo
375 HH- 600 yds against a hostile because of trajectory considerations, 300 yds max against a buffalo. BTW, in some countries in Agrica, the 375 H&H is the minimum allowed against buffalo, others call for a 40-caliber.
300 wethy. 1000 yds against a hostile, 200 yds against a buffalo