My wife has killed several bulls with a longbow, and two that most rifle hunters would consider the absolute bull of a lifetime.
She hunts with what I would consider the bare minimum for elk, and trains all year with weights to make sure she can do it.
Her longbows are 52 pounds at her 26" draw length, and the arrows she killed her bulls with were 600 grains and 625 grains fir or compressed lodgepole pine. The 625s perform the best.
She has never put a broadhead through the skin on the far side of a bull. Her LONGEST shot has been 15 yards (only six yards from where I was hiding and calling the bull) .
All arrows have penetrated both lungs, except for the largest bull elk I have ever called in, and she hit him square in the shoulder, totally broadside at 10 yards. That one stopped at the shoulder blade and after bolting about 100 yards, he continued to bugle at us.
If I found someone in the mountains hunting elk with a bow under 45 pounds, I would probably take it from him and-----with all due respect and as kindly as I possibly could,-----tell him to hike back to the trailhead and head home. Such bows are illegal here in Idaho for good reason.
I would ship the bow to him, and send him the best information I have on how to put on muscle and strength, and heck, I would probably even invite him out to pack in with my llamas and hunt elk the next year, but only if he put in the time and effort to build the strength to shoot an elk-weight bow well.
Simply put, for the sake of the animal that represents the very essence of wild county, you don't hunt elk with .22s, and you don't hunt them with 40-pound bows.
50 pounds with great accuracy and a heavy arrow? Now you're talking elk!