Early reports were 4 M-4s rifles and 10 M-9 pistols. Not sure I buy that since if they got into a vault, there would be a heavy machine guns in there too. A good opfor team would have grabbed a least one machine gun and more rifles.
Type of weapons in the arms vault depends upon what is authorized in the unit MTOE.
Line units have one or two pistols & over a hundred M-4s. I was in a JAG unit with a large number of M-9s for the attorneys.
A unit with a lot of vehicles will have several M-2 .50 cal.
IMO this was an inside job with a ringleader named either Tyrone or Mohammed.