When ever I signed out my issued weapon or my own personal sidearm, it was never issued loaded. No problem to get it on base though as he could have easily had them in his personal vehicle or on his person. Officers have to keep their weapons in the same arms room everyone else does if they live in the barracks or officer quarters. Or least at the posts I served (Ft. Sill, Ft. Bliss, Camp Colbern (ROK)). I know that Maj. Hasan *spit*, used pistols. What kind or caliber, I do not know. Probably Baretta 92s. The reason I say Baretta 92s is because unless he was a frequent shooter, those are the pistols he would be most familiar with due to his military training and qualification.
He had an FN 5.7 and a .357 of some sort. Not clear to me if the latter as a wheel gun or a .357 Sig. Not a duty weapon. He probably hadn't even been issued one yet, since he was not very close to deployment.