Built around a Peters-made 45 ACP casing headstamped "PETERS/45 A.C.", the Peters-Thompson Shot Cartridge replaces the standard bullet with a folded cardboard "pil"' that contains a load of 120 pellets of #8 birdshot per cartridge. Measuring slightly larger than a standard 45 ACP round, the Peters-Thompson could cycle through multiple models of Thompson SMG and Carbine with no alteration aside from a slightly longer magazine. The included example is blued steel and marked on the front "PATENTED-AUG.-24-1920/FOR 18 SHOT CARTRIDGES/AUG.-24-1920-JAN.-11-1921". The included Handbook mentions the cartridge, citing a six foot spread at 50 feet and a maximum range of 150 feet. Unlike many shot cartridges which were marketed as rat killers and survival tools, Peters marked theirs as "especially prepared for riot use… considered particularly effective for that purpose" right on the box.

The cartridges are fine with some light creasing and scuffs on the paper and a few dark spots on the paper and metal. One of the casings has been dented and scuffed, possibly from test cycling. The manual is about good with wear and tear on the cover appropriate to age and evidence of old removed tape repairs. The magazine is very fine with a few light handling marks and mild wear from use.