Not to sound like a jerk but I'm pretty sure that's a 20" barrel 500 and to my knowledge you can't use the longer bird barrels on it. The reason I say this is I too own a 7+1 mossy. Any 500 stock will fit though, mines a speedfeed with xtra ammo on both sides. I recommend the Blackhawk/Knoxx line of recoil reducing stocks as well. :-)