I'm at the point where I either have to buy a larger safe or start selling guns. On my doubles, I remove barrels and keep the action ends on the top shelf. I hang the barrels from what would be the top row of indented "rests" on the safe walls and middle divider. I have a three inch section (straight) of metal coat hanger wire secured in the middle to a length of 18 gauge enameled copper wire that has large barbless fish hook on the other end, point dulled. The coat hanger section supports the barrel at the chamber end. The wire is long enough to pull the non-hook end of the wire out enough to fold the coat hanger wire back inside the barrel to pull it out.
With the barrels hanging inside the indented rest, my pumps and rifles can fit barrel down, stocks against the top rest. There's also space against the inside jamb of the safe door to lean a few barrels. It's pretty much a blivet*. Gil
* Southernism: ten pounds of crap in a five pound size bag