30 Caliber Ammo Can MTM ammo cans are a great way to store bulk or boxed ammo. Its all-plastic design is lighter in weight than the 30 caliber US Military Surplus Ammo Cans. Transferring ammo to and from the range, just became a little easier! I deal for bulk 45 ammo. Molded out of rugged polypropylene plastic, these comfortably handled ammo cans will hold up to some pretty harsh treatment. Utilizing MTM's tongue and groove O-Ring seal system for a superior water-resistant seal, the 30 caliber can is designed to fit the same amount of bulk ammo as the originals. A heavy-duty dual-latching system makes for a better seal and is less likely to open accidentally. Double padlock tabs along with molded-in stacking ridges, make these solid containers the perfect solution to so many storage needs.