What you are dealing with is most probably a material called Bakelite, a very early form of plastic/resin. This from Wikipedia:

"It is a thermosetting phenol formaldehyde resin, formed from an elimination reaction of phenol with formaldehyde."

This is the stuff that turns brown when you expose it to the wrong solvents or heat. I'm guessing because of the formaldehyde element. You can stain it black, but it's still brown underneath.

I have a couple of Lefevers with brown buttplates, Parkers also. I would rather leave them as is than mess with them. Some have been boiled to make them that way, some came to me that way. I like them, no matter how they got that way.

John, Parker Bros. butt plates are made from "Gutta Percha" a form of rubber at least into the Remington era. The Parker marked plate's made by Remington may be bakelite.

I clean with a power toothbrush like I use for Checkering. For old buttplates I use orange hand cleaner with Pumice, rinse thoroughly then rottenstone in soap slurry, rinse thoroughly then a but of stock finish and they look new.

Harry;
I've heard of rottenstone before but where can one purchase it?

any serious wood workers supplies dealer

http://www.woodcraft.com/product/200...tone-1-lb.aspx

I got mine from Brownells

Basically you want mild abrasives in a NON petroleum liquid. The finer the abrasive the higher the polish and the longer it takes to remove the old oxidation. It seems to me I once used Bon-Ami cleaner too.

Assuming there's no crud on it, I use Kiwi black liquid shoe polish Take it off the stock before you use it!

Vintage gun grips is now taking orders for the 3 frame butt plate. Just incase you don't like that lovely brown look. Dave