06 SB
Lil-Rokslider
I have used Slick Trick Magnum on elk and many other heads on deer. It is important to have a very sharp broadhead and hit where you aim. I personally would use either a Slick Trick Mag or a Micro Hades. Practice at 80+ yards if you can to make a 40 yard shot seem easy. 50# will work just fine but you will need to get good estimating range in case you do not have time to use a range finder. If you do not have one of those, buy one.