I used to have an 870 with the Remington Stock on it, the reason it was issued was for helicopter and boat use, it was easier to get in and out of the Jet Rangers and it fit in the storage box on the patrol boats. Well it was not a very good solution, the stock was not rigid, and the rails of the stock would cut you when you shot the gun if you were not careful, problem solved by smoothiing and taping but it still wasn't comfortable to shoot. If you need, want a folding stock Choate makes or used to make a top folder that was much better than the Remington stock. I don't know how big of a space you are needing to store your shotgun in but that might help, if instant deployment is not needed, a better solution is to just take the barrel off and store the two parts together, obviously this doesn't work if rapid deployment is needed.
