No, ARH/Maccari. I have a couple old HWs where this seal has helped when modern HW seals dont seal properly without shimming.
The seal needs trimming in some guns, so like most ARH/Maccari seals, its made oversize so you can fit it.
Another tip if you need to increase seal length, is a couple rounds of dental floss at the bottom of the seal groove.
It sounds a bit McGyver'ish, but it actually works quite well, at least in break barrels.