At very close range, during my encounter, I was carrying a 4-inch .44 Magnum, loaded with 240 gr. JSP's. My first reaction was........"I don't have enough gun here! I had, and still don't have any ambition to shoot one. I did at one time, but my encounter changed that.
My gut feeling is that if you encounter a squatch, you will not want to shoot it. Don't get me wrong, the pucker factor will be high, and you will damn well be afraid, but your attitude will change in ways that I cannot explain.
Obviously a self defense situation will be very different. If your intent is to harvest one, my hat's off to you, but I cannot in good conscience recommend a rifle. If I had the room to carry a shoulder fired defensive weapon on a research expedition, it would be a short barreled slug gun loaded with 3-inch Brenneke slugs.