Hello HappyH
Have you tried other manufacturers that may have produced firearms with brass covered components? They may be able to do the job for you or maybe provide recommendations.
Also, try posting on this forum ...
http://www.shotgunworld.com/ .... although they discuss mostly shotguns, they may have experienced or heard of similar circumstances and therefore may be able to offer some advice.
Finally, what about other companies that work with brass, just not with firearms? The procedure may be the same or similar, and they may be able to help you out.
Hope this helps.