I have hunted with heavy and light slugs. both work depending on muscle mass, amount of muscle to the vital area you want to reach, the hide thickness, the "armoring" of the animal (pigs and bear specifically), and your range. Slow and heavy works well (150 or 170 grain 30-30) fast and light works (125 grain Accu-Bond from a 308 or a 300 W/M). my personal favorite for deer is the 100 to 120 grain slug from my 270 Winchester (Barnes slugs). How many of you remember before the TSX line that Barnes put out a 100 grain X, 110 grain X, and a 120 grain X for the 0.277" diameter bores? I also love the performance of the 338 diameter Barnes in my 338 Win Mag. I have experience shooting game with 257 Rob, 25-06, 270 Win/270 WSM, 30-30, 300 W/M, 338 W/M 45-70, 444 Marlin, and that is it. I never got to use my dad's old 30-06, or my 32 Win Special. but I digress. Copper mono's or Copper jacketed lead do well when properly applied to the situation. we are talking about a deer at what ever range, but with range and velocity/speed becomes a vital variable for picking the differently constructed slugs we have. The slug needs to be constructed at different speeds in order to the most effective job. the farther out the skin of the slug needs to be thinner at the tip than if it was closer to open up faster or at all when hitting either hard tissue (bone) or softer tissue (heavy muscle) what you are asking needs to have more information to it. you can not expect a slug designed to open at 2500 FPS to do the same thing at a yardage it is traveling at 1800 FPS or slower. with mono's (barnes and Hornady or Cutting Edge) those slugs are great for deep penetration and opening up violently upon hitting much of anything harder than moderately heavy muscle at short to moderately long yardages. then you have the copper jacketed lead cores that can be designed to never open up in the case of DG solid jackets (constructed like military ball rounds), then you have them as delicate as a varminting slug that will disintegrate at the hint of a bone. nothing is a perfect slug. there is give and take with each and every slug. you have to pick the slug that matches your particular situation at the time. My go-to slugs are Barnes, Nosler, and Berger. I have yet to find any slugs that perform better at the yardages and on the game I go after. a very long post but i could not condense it. is there anything I left out?