I don't know if this is what you are talking about or not but will make a stab at it! Back action locks obviously sit further back on the stock and the lockplate itself, provides no support for a bolster (holding the nipple) or a drum and nipple, depending upon what is used. A front action lock sits under the bolster or drum and nipple, providing support for it. Any flame from the cap going off is pretty much taken by the metal of the front action lock plate. When a back action lock is used, the bolster or drum and nipple is supported by the wood of the stock. When a cap goes off, that is the area that absorbs any overflash. A small plate, inletted at the front of the back action lock plate, under the bolster or drum and nipple, will provide some support to them as well as take any over flash from the cap going off, thus preventing (for the most part) deterioration of the wood in that area. I have been shooting and collection front stuffers for over 40 years and have examined many original longarms that were made with back action locks. Many of them were never fitted with anything ahead of the back action lock and under the bolster / drum and nipple and as a result, wood in that area showed quite a bit of damage and sometimes is non-existant in that location. The same would apply to a pistol,, deringer or long arm. As I said, I don't know if that is what you are asking about but hope it helps. Am new to this board and greatly enjoy the exchange of information - a great place to visit and am always learning something new! Thanks!
