Martini-Henry Mark 1 questions

I have a .577/.450 Mark I model Martini-Henry Rifle. It is missing the correct Butt sling swivel, the correct Cleaning Rod, and the bronze breech block pin is a reproduction (to replace a 'home-made' steel replacement). Is the correct Butt swivel identical to screw-in butt swivels that were used on some Enfield muzzle-loaders and Sniders? Could someone provide a photo of an original Bronze breech-block hinge pin? Does the groove for the pin retaining or 'lock' screw go completely around the Bronze pin or just part way?