Which drill and counterbore should I use when installing the rear screw in a buttstoc

[samari46]

Have a couple police turn in 870 12 guage riot shotguns and a couple are missing the rear screw for the sling swivel to attach to. What screw should I use to pre drill the hole with as I don't wish to crack any wood. One of the stocks and forearm has been refinished and again do want to crack any wood. Thanks in advance. Frank

[M-Tecs]

https://www.brownells.com/shooting-accessories/slings-sling-swivels/swivel-installation-tools/swivel-base-drill-bit-set-sku683000005-26682-51959.aspx

[quack1]

I've installed a bunch of swivel studs, so many that I bought them in bulk. Uncle Mikes are the most common. For the rear ones, I used an 11/64" bit for the threads and 15/64" for the shank, never had any problems. Just be careful you don't drill the countersink too deep. Before installing the swivel stud, chamfer the edge of the freshly drilled hole to prevent chipping the finish.

[samari46]

M-Tecs and quack1, many thanks for the tips. Already have the drills and counter bores as a set I bought years ago. So will check the drill sizes. Two 870 riot guns and one has the stud for the rear sling swivel and the other one does not,go figure. Thanks again. Frank

[Texas by God]

Lube the threads a little by scraping the stud on a bar of soap before screwing it in. Old tip from an old guy. The above advice is spot on. Uncle Mike's makes a front stud that fits through the mag cap and is secured with a snap retainer. You can also drill the mag cap hole out for the standard machine screw/ forend nut type- but you may have to modify your spring retainer if it's the plastic kind.

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[Tokarev]

Very thin-walled tubular drills can be made of steel cases, using a needle file or dremel. They counter-bore wood very well.

[samari46]

I usually take out the mag spring retainers. In my experience they get stuck and you have to fight to get them out. So once out just push down on the spring with the mag cap and screw it on. Buddy got one well and truely stick. Used a cutoff wheel on a dremel,took it out with needle nosed pliers and since the spring was undamaged put the cap on the top of the spring,forced it down and screwed the cap in place. Frank