Well Saddlesore makes a good point, and the 41% rule may be for beef only. I don't honestly know. Maybe the % will be a lot less on elk or deer then it will be on beef. Cows sure are chunker than deer so that probably is the case.

I always do my own butchering, but I don't weigh the meat. I cut and wrap for size not weight. (so it fits as I want it to in my freezers)