Bryan, we've taken a couple elk with a 12 gauge slug & one with a 20 gauge slug. The 12 really puts the hammer down on them for sure. You are definitely good to 100yds as long as you do your part. (grin) Here's a photo of one taken at 40yds that I called in for my nephew & his Dad. The cow dropped nearly instantly & the slug had complete penetration! It was sticking in the hide on the off-side!

ElkNut1