Drill your hole 4" up the stock from the butplate, if you dont have a drill bit for for installing them you can use a bit the same diameter as the swivel to start the hole, apprx. 1/16 deep, this will keep you from splintering the opening when you start the swivel,then drill the hole with a 5/32 drill to correct depth. When installing the swivel use either wax or soap on the threads to aid the install.