On Serial Number 1, Model of 1919 (the Annihilator 1), the box magazine made its first appearance. This first magazine was literally a folded-up box of metal. The magazine was held in place by a strip of metal locking into one corner of the loop. The floor plate of the magazine locked into two slots on the sides of the magazine.

SERIAL NUMBER TWO'S BOX MAGAZINE. NOTE THE SLOTS AT THE BOTTOM FOR THE BUTTERFLY FLOOR PLATE. THE CUT-OUT IN THE MIDDLE OF THE MAG. WAS HOW THE MAG WAS ATTACHED TO THE M1919.

One problem with this design was that it was possible to force the magazine into the firearm's magazine well backwards and the magazine catch was very fragile. By the time the patent drawings were submitted the design had become a bit more polished. The magazine exhibited the rounded front comers and a more pronounced back rib. The floor plate of the magazine was still of the butterfly design locking into the sides of the box. These magazines were made for M1919 Serial Numbers 3-7 filed May 15, 1919, U.S. Patent # 1,350,619 (August -24, 1920) granted.