That’s one heck of a small arms locker
Was reading up on 80-foot Nasty Boats (PTFs) used by the Navy during Vietnam and found the following tid bit from the most excellent N6CC.com site which covers military radios, MIUWUs, and a good bit of brown water Navy antics of the 1960s:
We carried approximately 20 M-16 Rifles, four .45 cal pistols, two .38 cal pistols, two M-60 machine guns, two M-79 grenade launchers, two M-870 12 gauge shotguns, a 40 mm Very pistol, a .45/70 line-throwing gun plus the .50 cal M2, two 20 mm cannons, the 40 mm cannon and the 81 mm mortar. Without a doubt, the most heavily armed vessel of its size anywhere.
Keep in mind these craft were slightly smaller than the Point-class Coast Guard cutters used in Market Time that we have covered here earlier.
Here are some shots from N6CC: