The Warrior having a coaxial piston arrangement has a main piston seal that seals the cylinder and an inner seal that seals the barrel to piston.
Both were leather.
The main piston was held on by a thick steel washer that was sprung over a segmented ring formed from the front of the piston. Bits of this could snap off and there was little you could do to fix it without major surgery. Power should be about the same as a Webley pistol but the trigger pull is very heavy.
Had some great fun with mine until it was retired!