I am returning to ML hunting after 30 years of bow hunting, back injury put an end to my archery days. Since I am starting at the bottom of the learning curve again, I dont have any 1st hand knowledge about ML hunting elk here in New Mexico, but one of my best friends is an outfitter in units 15, the 16's and 23. He has seen just about every caliber and load in existence used on elk on the ML hunts. He said a .50 puts elk down no problem, with decent load you stuff in it. When he uses a ML on elk he shoots a CVA .50 with a 100 grns of pyrodex pellets and a 250 grn sabot (I'm not sure which one he prefers). He said the only time he has ever seen a .50 fail to do the job was a women hunter he was guiding who could only handle the recoil of a 50 grn charge and 240 grn sabot. She hit one in the boiler room at about 80 yards, but they never did find the elk. Even put a dog on the trail with no luck.