I had to look twice at the pics of the stocks, I've just sent a William Powell to be re-stocked that had near identical rubber pads/blocks as those.
'Luckily' the one I had was cracked across the wrist and was missing a horn below a lockplate so needed to be replaced anyway.
What was the logic in fitting them ? Was it for grip or was the rubber soft when it was new, so could act as a cushion ?

Rust never sleeps !