Not a pad, since there's practically no give to it. It's labelled a No-Slip Butt Plate, and I'd call it a replacement buttplate. I did some searching, but didn't find any Fray-Merson buttplates stamped like this. Most of the stamps are vertical on the buttplates.
Here's one on a Win 52, but only a side pic.
https://www.gunsinternational.com/g...l-52--22-long-rifle.cfm?gun_id=100923381