I have gotten to the point where I shoot heavy bullets at reasonable velocities. I don't worry too much about penetration that way and a hole, particularly a big hole, through an elk or any other animal is gonna let cold air in and blood will be running out.
No reason why the .45 Colt, when loaded to it's potential will not kill all that needs killing.
Frankly, I would not be hesitant to take on an elk with my Marlin 357 carbine and a 180gr cast bullet over 15.7 gr of LilGun. I would not try a shot from the rear, but I could make that bullet whistle through his chest if I get a broadside shot.
For handgun hunting, I have pretty much settled on a .500 Linebaugh with a 400 gr bullet at 800-900fps. I cannot keep it in a hog from any angle and I don't think I could keep it in anything else either. I might put more steam on it for a big bear, but not much, certainly not over 1100fps.