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My first Polymer 80 Glock 19 clone build ...


The Lather Maestro
I've been wanting to do this for a long time, but some rumored changes in ATF rules regarding these prompted me to take action. Got a couple kits at a local gun show last weekend and spent this weekend putting it together. PDF directions are pretty good, although they left out a couple important steps, like how to assemble the trigger group. The Youtube videos on assembly by Pew-Tang Clan are outstanding, though. Very helpful.

So, what is it? It's an 80% lower receiver kit (I got the parts and slides for mine, as well) that you can finish yourself, and as long as you keep it in your possession, it can remain unserialized. I bought mine with cash, so no record of my purchasing them at all. [disclaimer] If you do transfer it to someone else, to remain legal, you must serialize it and transfer it through an FFL-1. [/disclaimer]. The lower kit comes with an unfinished polymer frame, slide rails, and other lower parts to make a complete lower receiver. You can buy a Glock complete upper receiver unit to put on it, or you can use various aftermarket slides/barrels/parts kits to finish your gun. The Glock complete upper units are unobtanium at present, as are many shooting items, but several manufacturers have good reputations for uppers, slided, barrels, and small parts.

The polymer frame comes in a plastic clamshell jig for drilling the required pinholes. The two required drillbits are also included, very convenient. You should NOT use a drill press, according to the instructions. They suggest a hand drill because it will align better with the jig. I don't have a drill press, so I was glad to hear that. Here are some shots of the work.




That last pic is one of my tips for anyone wanting to try this. It's super easy to remove some plastic strips with a whatever that is called. Flush cut nipper? Cutting pliers? I've heard it called a bull nose pliers. But it snips the plastic right off, that's one sitting on top of it.

Then you use files to smooth those down to the jig, and finally sandpaper them smooth.


More tips follow.
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The Lather Maestro
The hardest part of shaping the frame is the cutout for the area where the recoil spring and guide go. I used a short dremel round sander, then some small hobby files, but I could not fully clear it. I found a tip on Amazon for using long-shank grinders for a dremel tool. You could do it with a tapered round file, followed up by those hobby needle files, but it's time-consuming work, and I did not clear enough out and my slide is hanging up. So I ordered the long shank bits today. I'll post the range trip next weekend, hopefully. I will post the Amazon link to the bits and a review from another guy who used it just for this very purpose.

More in-progress pics. Front rails in place.


Magazine release in place.

Trigger group and other parts in place. Lower is done at this point. Use the Pew-Tang Clan videos. I can see how the next build(s) will be much easier, but I found this confusing from the PDF directions, and my son and I have built over a half dozen AR's, so I'm not inexperienced.
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The Lather Maestro
Tip #1. While you do not need a drill press, you do, IMO, absolutely need a good bench vise with soft grips. I simply cannot imagine doing this without a good, bench-mounted vise. If you don't have one, go to a buddy's house who has one and use his.


Installing some parts, like the slide takedown catch, I cannot imagine doing without a vise. That's what I was installing in that pic. And if you are going to dremel the cutout for the recoil spring and/or hand file, you absolutely need a good vise.

Tip #2 is be very careful with the small springs, they will launch! Handle only as much as needed to get them in place. I launched the firing pin safety spring doing this, and cannibalized the second kit for it. If I cannot locate it, I'm going to be really irritated. :mad:

Tip #3 is while you don't need a lot of tools, what you need, you really need. A good set of drift punches is a must have, and I think a gunsmith hammer, with brass side and polymer side is almost necessary, although I suppose a small hammer will work. They are using a carpenter's claw hammer in the Pew-Tang Clan vids, so I guess it's not really needed. While you can just use popsicle sticks, dowels, and sandpaper, I found the needle files very helpful. And while not absolutely necessary, I suggest a gunsmith mat is almost so, for keeping track of the small parts. I use this Ransom master mat.


Tip #4: And here, I differ from the printed instructions. The rear of the front rail/locking block did not line up perfectly with the jig-drilled hole. Neither did the rear rail piece. The instructions suggest that if they are slightly off (and it was slightly) you finagle the parts until you can line them up, they advise not redrilling. Problem is I could not get them to line up, and you're not going to drive a pin through metal. After realizing it would be impossible, I took it to the bench vise and CAREFULLY hand drill those areas. As expected the metal throws the bit off so you're drilling polymer, however, the pins were still very, very tight when I pounded them in. It would be nice if CNC machined parts lined up with an injection-molded precision jig, but mine did not. If you cannot get the part holes lined up with your frame holes, and you have a vise and a steady hand with a drill, I would not worry too much about redrilling them. I had no choice, so it's moot anyway.

Here is the link to the long-shank dremel burrs.

And a photo from the reviewer working on this very frame project with one of them. If you have a dremel, get these. If you don't, a round taper file and needle files will work, but be thorough in hogging out that area of the frame. I'd suggest you do it before installing the front rail/locking block like this fellow did.


His review: I bought these for a very specific application. To grind out the RSA channel on P940 80% frames. This area of the frame is particularly hard to get perfect. Tough to sand effectively and you can’t get a conventional dremel bit in there. The 4” shaft length is long enough to even do the P940CL.I highly recommend these, wish I would have found them many frames ago.

All in all, a fun, though at times frustrating project. I'll post the range report in this thread when I get to it. And I am quite certain the second one will go much better.
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The Men Who Sniff at Goats
I have seen some really souped up, race looking poly 80’s. Glockstore.com has a bunch of cool, jazzed up pistols to look at.


The Lather Maestro
Wow! This thing was not easy! They say it's easier than an AR-15 build, but I'd say no to that, at least if you use a commercial aluminum lower. Those are easy. So, first range trip I realized I needed to really clean up the channel for the recoil spring. Shot maybe ten rounds and went home to clean it up with an 8" tapered round file and needle files because the long shank bits did not arrive yet. That was successful.

However, the spring that holds up the slide release catch would not go deep enough to be flush with the bottom of the channel for the recoil spring, and I knew that would hang up the spring, and it was not providing enough tension for the takedown latch. So I carefully drilled that hole all the way through to the trigger guard with a 1/16" bit (you can hardly see it in the trigger guard), and now it sits perfectly along the recoil spring channel and provides plenty of tension.

Second trip to the range today, and 2/3 of the shots the slide would not go fully into battery. I could force it with my thumb, and then it would fire fine, but I found this curious because the recoil spring channel was definitely no longer an issue. Having had a bit of gunsmithing experience building AR's and doing revolver action jobs, and a little 1911 work was a help, and with a little searching on YouTube, I discovered that the part of the trigger bar that interfaces with the striker safety can get hung up, and this is not an uncommon issue. So back home to disassemble the pistol and polish up some parts. After carefully breaking down the slide parts so as not to lose any springs (I did find the striker safety spring the other day, thankfully), I stoned the striker safety plunger a bit, then took it to the vise with the padded jaws and polished it with a small Dremel buffing wheel and some AutoSol polish. I also polished the part of the trigger bar that engages with it. See below.


The slide was still hanging up sometimes on the last 1/8" travel, even without a magazine inserted. Knowing a little about fitting 1911 barrels, I suspected the barrel/slide lockup was too sharp. Not being an experienced Glock guy, I'm guessing here, but I suspect I am right. So, some light stoning of the areas on the barrel hood as well as the inside upper edge of the slide ejection port, and it is working perfectly with manually racking the slide. See photo below.


I am fairly confident this will do the trick, and it's back to the range tomorrow morning for about 200 more break in rounds.

While I had it disassembled fully, I took the time to take the rail sections back to the bench vise and used a drill to ease parts of the pin holes that were giving me fits inserting the pins--extremely tight. With a CNC machined commercial AR-15 lower, the Lower Parts Kit normally fits easy-peasy, and as long as you've done one, the next several builds should be relatively easy. With these polymer kits, the holes do not line up perfectly and you cannot force a pin through a quarter moon sliver of metal in the hole, and you don't want to enlarge the holes in the polymer. So getting the rail sections properly pinned is going to take some easing of the holes in the rail sections, and/or grinding on them to improve fit. Pewtang.com has a great video on this for the rear rail section. Edit: You can see these little moon-slivers of metal in the holes in the first photo in post #2.

Overall, this build has still been a lot of fun, but it has not been as easy as some of the reviews will lead you to believe. I have about 4-5 solid hours into this so far, but it's shaping up nicely, I believe. I would not suggest just anyone attempt one of these. You should be handy with tools generally, have a lot of patience, and some home gunsmithing experience is a good thing to have because it helps you figure out where things are hung up, like my fitting that barrel hood to the ejection port.

Hopefully, I'll have a positive range report to post tomorrow. This build is for my brother, and I talked him into getting some Trijicon night sights, so that will be the last part of this project. By the way, it shoots pretty accurately, and right to POA for the current sights. More tomorrow.
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