New made ones are available around $600.00. I bought one 6 or 7 years ago and it works fine. If you buy a new one, slide a cartridge around through the rails inside the drum to make sure there are no tight spots to slow or stop the feeding. If you find a slightly tight area, carefully move the rail slightly by moving the cartridge side to side to gain a slight amount of clearance. Make sure the drum fits/slides through the slots on the receiver and locks in place. Mine was tight, but I was able to get it in the slots and after several insertions it fit better. https://gunmagwarehouse.com/auto-ordnance-thompson-1927-a1-45acp-100-round-drum-magazine.html