You bunch of non reading hacks first to reply!
The Barrel on his shotgun is 18 inches. That is LEAGAL. It is as short as it can be.
He has a stock on his shotgun. He does not like the light weight manufacture of the mosberg that lends its self to heavy recoil.
1)Get the choate full length shotgun stock it is solid and has a vertical grip instead of a drop comb. Check out www.AR15.com in the weapons forums. We have a great community.
2) Get a remington 870. It has a steel reciever and is much heavier. It is my choice.
3) OR get four or five slug shells, unscrew the but pad on the hollow factory stock. Put them in the hollow. It adds weight and dampens recoil.