I've killed 2 bison cows with a .58; one in UT and the other in WY, both with a .58. The load is 110gr fffg, heavy denim patch, & .575 round ball. Even with a great shot, the animal will not fall dead. It will run until it doesn't, however far that is. If you spook them, they won't run 100yds, stop, and look back; they will run a 1/2 mile or more and then stop to think about it. Even just walking they can cover a deceptively large piece of real estate over a short period of time. Shot placement is everything. If you read the old fur trade journals, you will learn that greenhorns commonly shot all of their balls into and around a bison without ever bringing it down. That's because a bison is a veritable mountain of meat with a relatively small kill zone. The heart of a bison is way down low in the front of the animal, right behind the front leg & so low that you are sure that you are about to shoot under them. That is especially true with that big, wooly, coat hanging down under them. I would keep my range at or under 100yds & use a good rest like cross sticks if you can. Even if they take off at a dead run, don't assume that you missed. Follow them up a mile or so and check for blood. I shot a little too far back on my first cow & liquified her liver. She still went nearly a mile before she died & lay down once leaving about a 4 foot wide blood spot before that. If your animal goes down in a herd, they will probably circle it & try to get it up by hooking it with their horns. The more blood they get in their noses, the more aggressive they get, so let everything settle down with the herd going away before you go to the animal. I saw a gentleman in UT get charged when the hunter headed over to shoo the herd away from a downed animal. No physical injury, mind you, but I doubt that he ever wore those skivvies again. If you have drawn a cow tag, by all means learn some field judging. We had to spend a day at BYU learning field judging of bison with DNR, and one poor guy still shot a yearling bull, mistaking it for a cow. Cows generally have necks and their horns tend to curl more than a bull's. Mature bulls look as if their heads are glued to the front shoulders and their horns tend to be more vertical/less curled for business. The shaggy belly tends to hide male genitalia, so plumbing may not help. The bad news is that young bulls and cows look a lot alike & it's easier to make a mistake than you might imagine. And take plenty of manpower, good sharp knives & saws, & something to sharpen the knives with. Hanging the animal is really helpful but is sometimes impossible. I like gutting, skinning a quartering one side & then rolling and repeating. If you're doing a ranch hunt, you don't have to worry about that. A good front end loader works wonders for skinning & dressing. Finally, if you can't get the hide to a tanner quickly, salt it heavily with rock salt & put it folded & angled downhill into about a 5 gallon bucket. You will be amazed at how much fluid comes out of it. Repeat again when the drainage slows or stops. That is pretty much all I remember, so I hope you have a great time & many good meals to come.
Roger B.