Odd question... It's a auto-loading shotgun made from 1905-1947, actually it is the FIRST auto-loading shotgun produced in the U.S.A. !
See the link below for instructions.
Parker 12 ga muzzleloader
Follow the owner manual instructions using the link below
The New Victor Crescent Firearms Co 12 gauge, single shot shotgun is well suited for hunting small game and birds. The breech loading design is reliable and allows for quick reloading.
Contact Browning for an owner's manual. The bolt should be forward when loading the magazine, and then operated to load a shell into the chamber.
Follow the instructions in the owner's manual. If you do not have one, go to Browning.com and request one.
12
You need to get a letter from Browning. Date would be 1903-1910 or so.
12 gauge the higher the gauge the thicker the item is
12 gauge is thicker than 14 gauge.
12 gauge is thicker than 20 gauge. The lower the gauge, the thicker the sheet metal or wire.