Depends on the rifle I have at the time. If I take a 44-40 rifle, I carry a revolver in the same caliber. If I have any of my other lever guns, I carry a .45 revolver. I prefer a 5 1/2 inch barrel but like the 7 1/2 almost as much. Occasionally I'll pack a 4 3/4 incher for the heck of it.