[Legbreaker]

It all comes back to the original purpose of this thread I suppose - "long range" decisions ie a decade or three rather than the immediate future.
I agree that marksmanship ability may reduce, however there is a method called "dry firing" which can substitute somewhat for a lack of ammo. It's so effective when carried out correctly that the Soviet Olympic team used it as part of their training regime. Any of the older soldiers, or even civilian target shooters will be able to apply their knowledge of this to keep and improve general marksmanship.

Of course there's nothing like the real thing, nothing that can replace the feel of a weapon actually firing and the sudden recoil against the shoulder. With ammunition likely in short supply (in most areas anyway), accuracy with each round is even more important than it once was. Perhaps for the defensive role, low rate of fire tripod mounted weapons may be the answer. The tripod would minimise the felt recoil and increase accuracy well over that of a hand held SMG or assault rifle. The smaller weapons would still see widespread use, but they'd be secondary to the fixed defensive weapons.

Patrols and offensive actions would of course be a different story with operations carried out only by skilled soldiers who may have been retrained to conserve ammo, and thus extend the service life of their weapons. It may even be that semi-auto weapons become the norm, thereby preventing ammo wastage, with a handful of automatic weapons (GPMGs and LMGs) held in reserve/used as fire support. Essentially a move back to the tactics of the mid 20th Century.

Hunting is more likely to occur with non-military rounds such as .22LR which are relatively useless against enemy soldiers. Bows, crossbows and black powder weapons would see increased use by civilian hunters, along with traps of varying design. Organised agriculture would however be the prime method of feeding the population, especially in areas with greater population densities. In those areas it would seem unlikely the military would allow any weapons in civilian hands - keeps them more controllable and allows the military more weapon options (although really screws with the supply chain to have a dozen+ pistol calibres, etc...).