I have given some thought to this ridiculous premise but have come up with a set of 4 I could live with.............
1) RIMFIRE.......... Walnut stocked Sako Quad with 22 LR, 22 Mag and 17 HMR barrels
2) SHOTGUN.......Grade 3 Browning Superposed 4 barrel set.......410, 28, 20 and 12 all with changeable chokes.
3) HANDGUN......Large frame Super Blackhawk with 45 LC and 44 RM cylinders with interchangeable barrels and cylinder inserts for 357 and 9mm and 1/2 moon clips for 45 ACP
4) CF RIFLE.......Long action 700 Rem with standard and magnum faced bolts in a switch barreled set up. This would allow any cartridge from 22-250 to a .475 RUM
This action I would set up with a 1 piece Talley base and have a scope appropriate for each cartridge I had barrels for, set up in Talley QD rings. I was really impressed with repeatability of the Talley set up on my .470 NE, I would go with another similar set up.
I would have a Kevlar super ultra light stock for it, a medium weight fiberglass stock, a varmint configured stock, possibly thumbhole in glass or wood and I would have a nice custom walnut stock for the heavies, shaped along the lines of my Sako Safari.
I would also have several bottom metal assemblies for it, one of which would be a drop 5 round one, again along the same lines as my Sako Safari.
Action would be carbon steel and probably tefloned or cerracoated and all barrels would be stainless........but they could also be coated, depending on taste.......
I could live with this type of 4 gun battery, if it was Gov't decreed, (and only if we lost the revolution)................you see there would only be 4 serial numbers = 4 guns, right............
I think I may just build me one of these 700 set ups anyway, just for the hell of it..............