Clarification

The military maintains very discipline possession, control and maintenance requirements for all firearms . Turnover for a shotgun and a pistol is a scripted 3 person affair with checklists, special equipment, and 10 minutes of timing done precisesly, for example.

Having the same people handling and carrying another set of weapons without this level of control would be unduely hazardous (and it is hazardous, as any years mishap report summary will indicate). Chain of possession would be confused, unrated/uncertified weapons or ammo could corrupt armories. There's lots of technical reasons.

More seriously, most of the military are young people from diverse backgrounds with a lot of pressure on them. Even in ideal situations the anonymous but dense nature of military society can quickly lead to duress and stressful altercations that would be carelessly aggravated by the presence of firearms. The fact is, situations are hardly ideal; a lot of members are very young and come from troubled backgrounds. The structure and discipline of the military can develop such people into good citizens as well as good warriors, but they do not start that way. Even with strict rules there has been a lot of conduct problems at major training bases, very large commands (such as Aircraft Carriers) and overseas.

Plus a lot of military bases have especially hazardous materials, family housing , school and services, or prisoners. It just does not make sense to have lesser controls on guns at these places.

The problems with firearm proliferation, whatever they may actually be, are in these situations exacerbated.