I can't comment on the Rocky Mtn. but I would like to say that I am a Muzzy shooter, and have just went from the 3 blade 100gr. to the 4 blade 100gr. It is a smaller cut, but you get an extra blade. I have found the 4 blade to fly alot better than the 3 blade. On Tuesday I killed a deer with the 4 blade and was very happy with its performance.