What Size Are The Drill Bits For Polymer80 Glock Frames

Hi folks, a gentleman wrote me the other day that he had a PF940v2 Polymer80 frame but not drill bits and asked what size he needed. I checked and the rear trigger housing and front locking block pin needs a 3mm drill and the trigger pin needs a 4mm drill – note that this can also be written as M3 and M4 respectively. You’ll see M3 and M4 on the frames for example.

This was from my PF940CL build. You can see the two M3 (3mm) holes and the one M4 (4mm). Note, it is very important that you just drill a hole in each side. Do not try and drill straight through or you risk an alignment error and then things aren’t going to fit properly.

I visited the Polymer80 How-To page that has the frame completion guides available in PDF format for you to read and print. I quickly browsed the guides for all of the Polymer80 Glock-compatible frames (PF9222, PF940SC, PF940C, PF940CL. PF940V2 and PF45) – they all use 3mm and 4mm drill bits.

If you buy bits, you either want them a tad undersize (such as 2.99 and 3.99) or at the nominal spec for 3.0 and 4.0. If you get a cheap import bit that is too over-sized, you will run the risk of the pins being too lose. The bits that come from one of my Polymer80 PF940v2 kits measure 2.990 and 3.986mm according to my micrometer.

These are our 3 and 4mm bits sized 2.95-2.97mm and 3.95-3.96mm respectively.

We do sell quality cobalt bits that are excellent for this work. Click here for our listing.


Polymer80 frames are fun builds and you can create reliable and accurate pistols. The caveats are that you should read the instructions, take your time and use the right drill bits.

I hope this helps you out.

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