Load the 38 Special / 357 cartridge into the cylinder and shoot.
There is no need to use the safety pipe and nut with a 38 Special/ 357 cartridge.
The 38 cap that is part of the 38 Special/ 357 cartridge, is interchangeable with all of the other back caps that Laser ammo offers (9MTA, 9MTA/DB, 9MDB etc.)