Just as easy to pop off the recoil pad - remembering that it's plastic and brittle and snaps real easy - and fill it with whatever your favorite stuff is.

I filled one about a year or two ago with Liquid Nail. Don't ask me why. I just happened to have 8 tubes of it in the shop. I packed styrofoam in the end over the Liquid Nail to prevent it from running out and reassembled the recoil pad.

About 4 months later I drilled thru the stock to mount a Kydex cheek rest. I carefully marked my drill points and proceeded. As I pulled the drill bit back out it was followed by a glob of Liquid Nail and it cascaded down the sides of the stock.
The stuff won't harden without air.

Just a little useful info from yer 'ol Uncle Frank...