Recoil stop question

[Blueheeler 0]

There are three  recoil blocks or keys in the stock, two in the butt stock and one in the forearm-are they all the same part-i.e. are they interchangible?  Thanks.

[Joseph Scott 0]

The two over the trigger and in the forearm are 1/4" square.  The small one in the stock for the recoil tube is 3/16"  square and has smaller retainer screws.  The holes through the wood are square to prevent rotation of the keys.  The holes are counter-bored just enough for the screw heads to be below the surface. I have seen several stocks made by others which were incorrectly round all the way through.