I am wondering if anyone can help me with some tap sizes. I am going to be fitting some various steel grip caps and inlet swivel bases andd need to kknow what size to tap the screw holes on the stocks. Here are the ones I need to know the sizes for:

Tap for Winchester grip cap screw

Tap for Winchester swivel base screw (the coarse threaded screw for the rear base)

Tap for Fisher grip cap screw

Tap for Dakota swivel base screw

Tap for Talley swivel base screw


If anyone knows the tap sizes I need and share them with me I would really appreciate it.

Rather than using a tap I just run a #10 or 12 tapping screw into the hole to the proper depth and then back it out, "prethreads" the hole just fine.

Bill: These are USUALLY corase machine screws. Get a thread gag e, then measure the OD and you'll be able to figure out the tap size. usually 8x24 10 x24 AND 12X24...OR...measure the minor diameter, use some beeswax or similar as a lube and use the screw to "thread the wood" takes less time to do it than write about it...good luck!

The wood screws for most of these are not standardized or of the same TPI as standard taps. They are usually a coarser pitch. What DUane says is good advice; beeswax will allow the screw to go in a lot easier.

The Dakota screws are 8-24. It's not a standard size. Almost more important than a tap is a hardened CORRECTLY SIZED drill bushing to properly locate the holes. For taps I made one out of stress proof for the 8-24 and used a socket head cap screw 10-24 and dremeled a few flutes into it for the big screws on a McFarland buttplate. I use a cordless drill with a cut off allen and zip it in and out. Using a drill with a small tap is a sure way to break it. Trust me, it's not fun to remove.

8x24 taps are readily available as are 10-24, 12-24 etc..no need to re invent the wheel..just go to mscdirect.com

[QUOTE] use some beeswax or similar as a lube and use the screw to "thread the wood" QUOTE]

If you can't find beeswax, any bar soap will work just fine. Pull the screw across the soap, drill a starting hole smaller than the minor diameter of the screw (there are lists for this, but I usually eyeball it) and drive it in. The friction heat will melt the soap lubricating the threading process. I think comressing the wood fibers with this holds better than cutting the fibers of the wood with a tap. Use of a lube helps "form" the thread as the screw is driven. I don't claim to have seen any research on this, but I believe tapping the wood removes too much of the strength. What is plenty of material for steel is just not enough for wood (except pehaps Lignam V or similar exotic very dense hard wood). Compressed and formed threading is "more better"


Roger

The Dressel / Mc Farland screw sizes are as follows.
Small is 7 x 24 TPI
Large is 10 x 24 TPI
P.S. they have been machined from LaSalle 1144 so do not caseharden them.

Winchester pre 64 Super Grade Swivel base screws, there are two sizes/ types
Up to early 50's, .217 x 11 TPI, modified Acme, with a taper to the point.
Later ones are a rolled two pitch thread, with a taper to the point.

But Beeswax works great and I have more than enough to last my working days.

The most important part is getting the proper sized holes drill correctly, this means using a milling machine or drill bushings.

James Wisner
Custom Metalsmith

Thanks for the info and sugestions. I had completely forgotten about using soap or wax. I am going to order a swivel screw drilling jig from brownells before I do anything though so I dont drill the holes off at an angle.