Reviving an old thread here to avoid having to start a new one.
To restore an original Lefever butt plate that was in similar condition as Dave's in the first post in this thread I used tooth paste and DOT 5 brake fluid with silicone. This is an auto restorer's trick to restore rubber and Bakelite items such as knobs etc.
Tooth paste is a mild abrasive. I used Crest 3D white.
I applied and rubbed with a cotton cloth. I used 3x3"cotton patches that you normally use to clean the barrels. As you do this, you will see the grime and residue on the patch. Rinse with warm water and check results. Keep going until you see the black. More elbow grease will be needed for the checkering but eventually it comes off.
After complete with the toothpaste, the black color is there but may look faded in some areas. DOT 5 brake fluid with silicone has great restoration abilities for natural rubber. I moistened a patch and massaged the oil on the butt plate. Put it away for a couple of hours and wipe the oil off.
You are done. The front of the plate matched exactly the color from the plate in the back. Also the sheen of the plastic is exact front and back.
This butt plate is being put on a Lefever E grade (not in this pic) that has a stock so oil soaked it was weeping from the side plates and grip cap. Also it hasn't been cut. Since the stock is being restored, I figured I do the butt plate as well.
Frank