a duct of large internal diameter into which a cartridge shaped percussion cap can be inserted and a firing ridge against which the rim of the cartridge shaped cap is forced to ignite the cap application_number US 89038378 A description referring now to the drawings fig1 shows an old style nipple 10 constructed for use in conjunction with the old style bucket shaped percussion cap 11 the old style nipple 10 possesses a uniform diameter hollow passage 12 extending axially through the nipple the nipple 10 had a threaded portion 13 for securing the nipple into the breech 15 of the gun 16 see fig2 the bucket shaped cap 11 containing a small quantity of gun powder not shown fits over the nipple 10 with the protruding portion 17 of the nipple passing inside the bucket shaped cap 11 the bucket shaped cap 11 has one covered end 18 but its other end 19 is open to the elements fig2 shows the new type nipple 22 of the present invention to be used in conjunction with a waterproof cartridge shaped percussion cap 23 the cartridge shaped percussion cap 23 has the general shape of the rear portion of the shell of a 22 caliber cartridge the percussion cap 23 has a cylindrical body 33 which is covered and sealed at one end by a cover piece 34 having an annular rim 35 which overhangs the cylindrical body 33 the other end 37 of the cylindrical body 33 is pinched shut so as to create a relatively waterproof seal to protect the small quantity of gun powder not shown which is held within the cartridge shaped percussion cap 23 the.