I have to say I agree with some things Mcseal2 says. The scabbard, unless you're young enough to be flexible, can be a bit of a pain to quickly pull your rifle. Some packs, my GS II and J107 both use compression straps that "can" also compress scabbard and keep the rifle from flopping around. When the straps do compress the pack contents against the scabbard, pulling the rifle is near impossible while it's on our back. Also, the scabbard, as nice as it is to have your hands free, can be a bit of a pain when one wants to sit down. The rifle or the pack has to be removed to do so.
Don't get me wrong, I'll still be using either pack this hunting season. I've carried an elk out with the J107.
Alan