Polymer80 PF940C Compact Gen2 80% Not A Glock - Part 1 - Frame Build

Up until recently, I've been mostly Glock-centric.  I've owned other polymer striker-fired handguns, but I've always circled back to the Glock platform.  I've never considered Glocks to be "perfection", and over the years I amassed an assortment of OEM and aftermarket components.   When I finally got around to organizing my parts drawer, I found I only needed 11 parts to build another Glock.  A few internals, slide and frame.  As fate would have it Polymer80 announced a %20 off Labor Day sale with free shipping on their new PF940C 80% frame.  I was not-interested in their original frame because the rear slide rails were simply machined into plastic.  I also wasn't a fan of the grip design.  It didn't seem to offer much improvement over the factory Glock frame aside from deleting the finger grooves.  Also, they sold for double what you could buy a stripped Glock frame for.  Oddly enough, complete Glock frames can be had for around $200, the same as a Polymer80 frame with lower parts kit, and that's before shipping to your FFL and transfer fees..

This new version however intrigued me.  The plastic rear slide rails were replaced with a steel insert.  It also already had all the modifications I do to my Glock frames.  Trigger guard undercut, milled accelerator cuts, finger groove delete, and 360 degree stippling.  It also has a thumb cutout for the mag release.  I actually prefer this arrangement over the Gen4 release.  They also filled in the "thumb divot" near the top of the grip, and straightened out the backstrap.  The only problem was I didn't have a Gen3 slide, and I wasn't going to spend nearly $300 for one.  However, as fate would have it, a smoking deal on a used gen3 G19 slide popped up in my Facebook feed.  I shrugged my shoulders, and after a few clicks, the frame and slide were on their way to my front door.  I also ordered a few required frame internals from Glockstore and slide parts from BigTexOutdoors.

There's something poignant about walking up to your front porch, and seeing a USPS box containing a soon to be firearm under an American flag.  Yes the mail carrier left it on my porch.  Good thing it wasn't a gun...yet.  I opened the box and was initially impressed.  The jig held the frame tightly, and the polymer frame felt, well, like a real gun.  I grabbed my 4th gen G19 and immediately compared the two.  I squeezed the magwell and noticed much less flex with the PF940C.  I also couldn't flex the pic rail/dust cover so "pignose" isn't in the future for this gun.  The rail is also parallel to the slide.  It always bugged me how the Glock rail points my lights up at about a 5 degree angle.  It's not a big deal, especially at handgun distances, but when running my suppressor, it results in slightly more barrel shadow than i feel like there needs to be.  The non-textured areas are slippery, either from the polymer formula, or the mold release agent.  Griping the PF940C was a revelation.  I've always preferred the 4th gen Glock grip to the 3rd gen because of the smaller hump on the rear of the grip, but I preferred how the gen3's upper backstrap fills the web of my shooting hand better.  The solution would be to run a cut-off upper medium backstrap on my gen4, but they never stay in place, so I've done without.  With the PF940C, I get the extra trigger reach and web filling grip, without the hump forcing my front sight skyward.  It's still feels distinctly Glock-like, but for my size L hands the ergonomics are much improved.  The texturing is sharp and moderately aggressive.  It feels like 20 lpi waffle stippling.

"Frame" mounted in Jig

Another improvement for me is the rear of the magwell.  On factory Glocks, I run an Agency magwell.  Not for faster reloads, but to prevent the skin of my palm from bulging under the grip and touching the magazine basepad.  I have to shift my grip, or they wont drop free.  This doesn't happen with the PF940C.  I did have one magazine that wouldn't drop free even when loaded with ammo, my OEM 31 rounder.  My OEM 15+2, and Magpul 21 round mags dropped freely.

Since my slide is still in transit, I wanted to see if i could use one of my gen4 slides.  The picatinny rail groove is too deep to mill away enough material in the dustcover, and there isn't enough metal to remove on the slide either.

Gen4 Slide? Nope.

Milling away the "rails" was somewhat painless.  Really they are just tabs that prevent the slide from being installed.  A Dremel tool, or even a file or sandpaper is enough to remove them.  While Polymer80 recommend just clamping the jig in a vise, I recommend using a clamp or two to hold the top half together.  I used a vertical mill to cut off the rails, and there was enough flex to chatter the part as the frame moved about.  A c-clamp took care of that.  Speaking of milling, the included 9mm HSS endmill is good enough for the job, but I won't be using it to cut anything but plastic.

9mm HSS Endmill - 3mm & 4mm Drill Bits

For the recoil spring tunnel, I used the mill to hog out most of it, then finished with a Dremel tool.  Since there isn't enough room to lay a sanding drum flat, I used a flex-shaft and a conical stone to finish the opening.

Tabs and Tunnel to be removed

The frame holes were easy enough to drill.  Polymer80 recommends using a hand drill and doing one side at a time.  The jigs holes guide the included 3mm and 4mm drill bits pretty well with one caveat.  The locking bock area of my frame was bent slightly inward.  After drilling the holes, when I inserted the front locking block, the trigger pin holes weren't perfectly aligned with the block.  When the block was inserted, it spread apart the frame slightly, changing the angle of the drilled holes.  I installed the block part way, clamped everything back into the jig, and chased the holes with the 4mm bit.  After that, the trigger pin slid right in with minimal resistance.

Ready for Milling and Drilling

The two solid steel pins take more effort to drive into the frame.  I'm used to not needing a hammer with my Glocks, but one is required to get them seated in the PF940C.

Rail Inserts with Pins

While I tried my Overwatch TAC trigger, I decided to stick with a stock (G17) trigger.  The guide rod is stainless simply because I had it already.  The same goes for the threaded barrel and night sights.  The only frame parts I bought were the mag release and spring, take-down spring, and trigger housing.  In total, completing the frame took about as much time as driving to my FFL and waiting for a NICS check.  Assembled, the trigger and slide feel exactly like a factory Glock.  What different is how the gun points.  It no longer points skyward.  The flattening of the backstrap, coupled with the Gen3 grip circumference, means my sights are dead on from the holster.  Speaking of holsters, the only way I can holster this gun is to mount a TLR-1 weapon light and run it in my Armordillo Lux.  The front of the dustcover isn't narrowed like on a standard Glock, and adds about 3/16" of width.

I'm pretty excited about this frame.  The FFL-less nature of this gun gives me a sense of freedom, like driving around in a $200 car, so I'm free to experiment.  Grip chop? Try a new stipple pattern? DIY Cutaway gun? Sims conversion? Dye a white frame pink?  Go nuts.  A new frame is never more than a few days away.  Shooting impressions to follow.

Uncut "frame"

Locking Block and Forward Rail Insert

Locking Block and Forward Rail Insert

Rear Rail Insert

Rear Rail Insert