Originally Posted by RatherBHuntin
Upon closer inspection, it is some type of plastic. Not sure what this came off of, but I am beginning to think it not one of my rifles.?.

https://www.24hourcampfire.com/ubbthreads/ubbthreads.php/galleries/14674650/plastic-shim


Looks flat in the photo, so if it did come from the stock/receiver interface of one of your rifles, it would probably be one with a flat bottom action. Can't say I've seen one like it, for what that's worth.