Originally Posted by billrla
I found the web link you need at MidwayUSA to purchase a drill bit kit to drill a hole in your 10/22 receiver. Just go to MidwayUSA and do a search on "Gunsmither Tools Ruger 10/22 Cleaning Rod Hole Drilling Fixture"
Those tools and guides are good to have if you are doing a number of rifles or are a gunsmith. They require removing the barrel to use and are a needless expense for only one or two guns.
Find the proper drilling location with a good ruler and center punch from the rear of the receiver and use a standard 1/4" drill bit. I started with a 1/8" hole and enlarged it in two steps to 1/4". The receiver is aluminum and drills easily from the back and you only need to disassemble the rifle as you would for cleaning.