ummmm what goes here?

[enbloc8]

That's where the fire selector switch would be on a real GI M14.

ETA: phony switches use to be sold to fill up the hole but I have no idea if they are still made or where to buy one.

A vendor named "sparrowhawkm14" used to sell them, but I have no idea if he still does.

I wanted a fake selector lock to put in there instead of a "happy switch"...in the end I decided it wasn't worth the bother.