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We are a national retailer of individual components and not all products depicted on this website are legal in every state. Shipping of various products found on this website are prohibited to some states (such as California, Connecticut, New Jersey, New York, Pennsylvania, and Washington). The information, pictures, text or products presented on this website are not a representation by us, and should not be understood by you, that any product or completed firearm is legal to assemble or own in your state of residence. We encourage each and every builder to perform their own research about the state and federal laws that apply to them. It is your responsibility to understand the law and we encourage you to consult with an attorney or your local ATF representative.

How to Complete a P80 Pistol Frame

Posted by AR-15LowerReceivers.com on Jul 27th 2020

How to Complete a P80 Pistol Frame

This visual and instructional guide illustrates how to complete the various series of 80% frames from Polymer80. These frames are 100% compatible with corresponding GLOCK®Gen 3 handguns. Complete build kits can be purchased which include the 80% jig, frame, tools, and all GLOCK®parts required for assembly your pistol.

Frame and GLOCK compatibility:

  • PF940C is compatible with GLOCK® 19, G23, and G32 handguns.
  • PF940v2 is compatible with GLOCK® 17, G22, G24, G31, G34, and G35 handguns.
  • PF940SC is compatible with GLOCK® 26, and G27 handguns.

Before starting, confirm the 80% frame you purchased matches the GLOCK® series or model you want to build. A partially machined frame is considered a firearm under federal law. Your frame cannot be returned or exchanged once you begin machining.

Tools Required

You'll need a few tools to complete your 80% frame:

  • Handheld drill
  • Work-holding vise
  • Round and straight or sandpaper
  • Drill press, Dremel or cutting snips

The drill press, Dremel or snips will be used for cutting the frame rails. A drill press and end mill can be used to cut the barrel seat, or the barrel seat can be shaped and sanded by hand using round files and sandpaper. Sandpaper is recommended in either case, to remove plastic burs and rough edges. Light sanding of the frame may also be required to fit certain components during final assembly.

Your frame and jig kit comes with the required drill bits for drilling the frame. It also comes with pins and a locking block rail system and rear rail module to install the barrel, trigger mechanism, and slide.

Completing the frame requires these steps:


  1. Drilling the trigger pin hole
  2. Drilling the locking block pin hole
  3. Drilling the trigger housing pin hole
  4. Cutting the slide rails
  5. Cutting the barrel seat

Completing the Frame

Step 1: Secure Frame and Jig w/ Vise

First, secure the frame inside the jig. The left and right jig plates should clamp to the frame like shown above. To keep the assembly secured, it may help to tape the two halves together. Use only moderate pressure to clamp the jig in your vise, horizontally first. Do not over-tighten the vise. Over-tightening the vise will warp the jig and frame, causing improper cuts and poorly drilled holes.

Step 2: Drill the Pin Holes (Read First!)

Utilize the M3 and M4 drill bits provided with the jig to complete the pin holes for the trigger mechanism housing and trigger itself. Do not use a drill press. Using a drill press may cause run-out and prevent the holes from self-aligning the bits, ruining the frame. Do not attempt to drill the frame's holes through only one side of the jig. Use only a handheld drill with light pressure to complete the various pin holes. Drill each hole by only going through the frame half-way on each side of the jig. 

Step 3: Cut the Slide Rails

The raised material located atop the frame needs to be cut so it is flush with the rest of the frame's slide rails. This step can be completed with a drill press and end mill, or with a Dremel or simple cutting snips. Caution should be used when using a Dremel; this tool will quickly remove polymer from the frame. Sandpaper should be used to lightly polish and smooth the cuts to ensure they're flush with the rest of the frame.

Step 4: Cut the Barrel Block

The last step before final assembly requires cutting -- or really, rounding out -- the barrel seat. Inside the barrel, the barrel seat is filled in with a thing layer of polymer. This polymer needs to be removed. Reference the graphic above and note the polymer highlighted in red should not be removed. Only cut the smaller layer inside the barrel seat.

This can be accomplished by positioning the frame and jig vertically in the vise, with the face of the barrel seat aligned with your drill press and an end mill bit. Or, a Dremel or round files can be used to remove the polymer by hand. Using a drill press and end mill will provide the greatest level of control while cutting.

Step 5: Install Locking Block Rail System

With the barrel block cut and sanded, your frame is now ready for final assembly. First, install the provided locking block rail system (LBRS) into the front of the frame above the trigger well. The LBRS incorporates both the locking block and slide rails. The holes in the legs of the LBRS should align with both holes drilled into the frame just above the trigger well. The LBRS may need to be lightly tapped to be fully seated. Once seated, verify alignment of the pin holes and gently tap one of the provided 3mm x 25mm black pins into the front hole and legs of the LBRS. Once seated, the pin should be flush on both sides of the frame.

Step 6: Install the Parts Kit & Rear Rail Module

To install the rear rail module (RRM), you will need a frame parts kit that includes the trigger, trigger mechanism housing, magazine catch components, and all other parts required to complete your P80 pistol build. Slide the RRM around the trigger mechanism housing. Install the trigger, trigger bar, and RRM into the trigger hole and rear housing hole. Light sanding above the magazine well, on the interior of the frame, may be required to fully seat the RRM; it is usually a tight fit. The RRM will be secured in tandem with the trigger housing mechanism and provided 3mm x 25mm pin via the rearward M3 hole you drilled earlier.

Troubleshooting RRM & Trigger Housing

Installing the trigger mechanism housing, rear rail module (RRM), and pin can be a very tight fit. If you meet excessive resistance or binding when attempting to install both units or when tapping the pin into place, use the list below to troubleshoot the most likely causes:

  1. Ensure both the RRM and housing are fully seated so the pin holes are aligned.
  2. If installing the pin from the left side, attempt to instead seat the pin from the right side.
  3. Use a small punch to keep all pin holes aligned while driving the pin in from the opposite side.
  4. Install the RRM by itself, insert the pin, then remove the pin. This will seat the RRM if it is tight-fitting.

If the trigger mechanism housing and pin cannot be installed successfully with the RRM after attempting the four steps above, remove the RRM, housing, and pin from the frame. Attempt the installation of the parts and pin after executing each step below until successful:

  1. Press and rotate the M3 drill bit through the pin hole by hand to de-bur and clean the hole.
  2. Lightly sand the exterior of the RRM to improve fitment. Its plating can be removed without affecting function.

DISCLAIMER: If you are new to the world of DIY gun building, you likely have a lot of questions and rightfully so. It’s an area that has a lot of questions that, without the correct answers, could have some serious implications. At 80-lower.com, we are by no means providing this content on our website to serve as legal advice or legal counsel. We encourage each and every builder to perform their own research around their respective State laws as well as educating themselves on the Federal laws. When performing your own research, please be sure that you are getting your information from a reliable source.

We are a national retailer of individual components and not all products depicted on this website are legal in every state. Shipping of various products found on this website are prohibited to some states (such as California, Connecticut, District of Columbia, New Jersey, New York, Rhode Island, and Washington). The information, pictures, text or products presented on this website are not a representation by us, and should not be understood by you, that any product or completed firearm is legal to assemble or own in your state of residence. We encourage each and every builder to perform their own research about the state and federal laws that apply to them. It is your responsibility to understand the law and we encourage you to consult with an attorney or your local ATF representative.