bellydeep,
On average, I've never found a monolithic that killed as quickly as most lead-cored bullets when using rib shots, given the same bullet weight and velocity.
But give a mono some real zip and they can do pretty well! One of the most spectacular kills I've seen occurred when my wife shot an average-sized mule deer buck with a 100-grain TSX started at 3550 fps from a .257 Weatherby. The range was about 160 yards, and Eileen put it right behind the shoulder. The next thing we saw was four hooves waving feebly above the sagebrush.
I know a lot of people who think monolithics (or similar bullets such as the Fail Safe, which worked exactly the same way) are quick killers. But I've been using them since the late 1980's, when the first Barnes X's appeared, and prefer not to use any from .30 caliber on down unless they're started out pretty fast.
