Converting Hatsan 95 stock to 1000x barreled action, part 3

Hello,

     You talk about the U shaped plastic piece. You suggested that it is used to shim up the rear of the rifle. Are you sure that is its purpose? I ask this because I just made a gun stock for the Hatsan 125.  The U shaped plastic piece is the same shape as the cut outs in the plastic stock.  ( I also have the Hatsan 95 and compared it's plastic piece with the cut outs in the 125's plastic stock.)   The cut outs and the plastic piece seem to butt up to TABS that are welded on the receiver just in front of the trigger assembly. I believe the U shaped plastic piece acts as a support on the wood stocks for the recoil action.   If you know something I don't then please school me.

Thank you