View Full Version : which size tap to use?

December 27, 2004, 07:51 PM
I have learned to point shoot with my Keltec P11 over the years because the sights are sooo poor. I have been looking to replace the front sight as inexpensively as possible. Came up with the bright idea to use a HiViz shotgun bead - installed it very temporarily today and went to the range to test. Actually worked quite well! Now I need to know what size of tap to install.
The HiViz came with 5 different size screws to fit most any shotgun - 3-56, 6-48,5-40, 3mm x .5, and 3mm x.6.
The Keltec slide has two unthreaded holes each one "about" .095" diameter. I would like to tap the forward most of the two. Suggestions from anyone on which size tap?


Lazy D
December 27, 2004, 08:39 PM
I would suggest the 6-48. Ideally the more TPI would be better but if you holes are already a .095 they are too big for the 3-56. 3-56 requires you to use a #45 drill (.082) The 6-48 uses a #31 drill (.120). If you don't have the required taps and bits the 6-48 tap and #31 drill bit are fairly common. That would be the easy route. Good Luck.

December 28, 2004, 07:09 PM
Lazy D -

Thanks for the info. Given the info you sent me and one other gentleman on another site, I did some re-measuring and decided that the 6-48 might remove more metal than I felt safe with (since I know zip-nada-bupkis about metal strength or drilling/tapping) so I "split" the difference and ordered a 5-40 tap and a #38 drill from Brownells. I will let you know how it comes out for better or worse.


mill hunky
December 29, 2004, 12:40 PM
www.michigandrill.com has a chart. on sae and metric taps

December 31, 2004, 02:53 PM
That was easy enough. Once I got the drill, tap,T-handle, cutting oil - took all of 5 minutes. Looks good - now I just have to get to the range to test it.