Which size tap to use?

[jim-alex]

Trying to do something about the poor sights on my Keltec P11. I have gotten decent at point shooting but I prefer a good front sight. I came up with the idea of using a HiViz shotgun bead - I installed one temporarily and went to the range. I actually worked pretty well. Now I want to install more permanently.
The Keltec slide has two unthreaded holes of "about" .095" diameter. I want to thread the forwardmost hole for the Hiviz. The Hiviz came with 5 screws to fit most shotguns - 3-56, 6-48, 5-40, 3mm x .5, and 3mm x .6. I really cannot figure out tap sizes. (The 3-56 is too small - don't think it would grab threads).
Anyone able to help?

Jim

 

[redneck]

You need to measure the diameter of the hole. Then there are charts that will tell what size tap will work. Might not fit any of them, takes pretty close tolerances to make it right.

 

[Bemo]

ooooh, I like...

This sounds potentially like a great mod. Please let us know how it turns (pun not intended) out.

 

[Razor 10]

Use the m3x.5 tap it requires a .0945 or 2.4mm hole. You should be able to run it right in. If you need assistance call me at Metrics Unlimited
1-800-638-7986. Just ask for Nick, we sell metric fastners and cutting tools. We are in the Detroit MI. area.


Good Luck
Nick

 

[jim-alex]

Mr. Razor:

Thanks for the info. I think you nailed the size. It appears that the 3mmx.5 would work without drilling. But since I don't really have confidence in my measuring accuracy, I decided I better use a tap/drill that removes a small amount of metal and then at least I know I have the correct size hole. Decided to use a 5-40 and a #38 drill. Thanks for your response, between you and the Brownells Catalog, I have a rudimentary, at best, understanding now of tap/drill. Now we will see if I can do this without screwing up. I'll let you know how this ends up.

Thanks.
Jim

 

[jim-alex]

That was easy enough. Once I got the drill, tap, T-handle and cutting oil - it took all of 5 minutes. Have not yet tested it at the range. If it works out, I think
my P32 is going to get a sight too.

Jim