The only solution I got with my cooey 39 is to go at the gunsmith shop, he drill and tap 4 hole to put weaver base on it,I guess is possible to put a willams receiver peep sight on it by the same way but I dont know each one can fit on the receiver, the willams receiver cost around 70$ (i just buy one for my Henry) and each hole cost me 15 $. It have some peep sight sold for the ruger 10/22 it fit on the regular sight grouve but I will be far from your eye and I have no idee how it will math with your front sight