The Navy and Marines usually used the same weapons. (although my K-Bar is marked "US NAVY-MKII" and was issued with a grey baked on finish scabbard) I don't believe the Navy would waste time repainting ammo cans, so they were probably the same colors as used by the Marines. (I never saw a grey .30 or .50 ammo can when I was in, unless it was repainted for personal use-we used them also for tool boxes as the were water proof, and usually repainted them down the engine room, but the majority of our our 20mm were grey- these we would fill with ice and use as coolers on the beach for beer) When I was assigned to the "World Famous Boarding Party" which my one ship had to supplement our "Extremely Small Marine Detachment" my web gear was all Marine Issue. Our Tin Pots were grey so the grunts could keep an eye on us. :-) :-) (this was a fun detail to get as we spent a lot of time on the fantail shooting all the weapons we were suppose to know how to use, and for a snipe that was a blast! And the second benefit was when I ended up in the Brig, the grunts knew me, so they treated me pretty decently! :-) )
As for belt or linked, I believe as the war progressed eventually the canvas belts were phased out of use.
Helmets on the ship were stored in racks, when not in use, and were either grey or OD. The CO, XO, OOD and Coxswain usually had those markings on their helmets. I believe the Navy beach-masters also had their helmets conspicuously marked for instant identify, as did the pecker checkers in usual white with red cross. The sound powered phone talker helmets were grey, I never saw any other color, and these would be marked accordingly to what phone circuit they were on.
Weapons were also kept in the armory when not in use, and were issued as needed, so chances are you never received the same weapon each time. Our web gear was kept in the "Boarding Party Supply Locker", which was next to the ships armory.
