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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 Build a P80 Pistol

Posted by 80 Lower Jig, Co. on Jun 4th 2020

How to Build a P80 Pistol

Polymer80's  "P80" pistol kits and frames are Glock®-compatible and boast the unique ability to interface with all of the Austrian gun maker's slides, internals, triggers, magazines, and accessories. Of course, the big selling point is your ability to legally buy a kit or 80% frame, cut and drill it at home, and turn it into a legal-by-definition firearm. You don't have to conduct a NICS background check, interfact with an FFL, nor fill out any bureacratic government paperwork.

The process of building a gun at home without paperwork has been legal for many years, yet little-known. The Gun Control Act of 1968 solidified this right and today, the  ATF clarifies it is still legal to do. So, how do you manage? Let's dive in. First, let's review the available kits and which one you need based on your GLOCK®preferences.


Polymer80 Pistol Kit Glock® Compatibility

Each P80 pistol kit correspond with a particular Glock® series of handguns. Use the list below to determine which kit you should use to build your pistol of choice:

  • The PF940C kit is compatible with the Glock® Gen3 19, G23 (3-Pin), and the G32.
  • The PF940v2 is compatible with the Glock® 17, G22, G24, G31, G34, and G35.
  • The PF940SC is compatible with the Glock® 26 and G27.

The kits include all the parts you need to assemble a finish, functional pistol, including sights and a magazine. If you want to stick with buying your own parts and internals, you can opt to purchase only the 80% frame. It still comes with the required jig for cutting and drilling, as well as the tooling, bits, locking block rail system, and drop-in rear rail module for the slide.


Tools Required for Completing The Frame

Once you've selected your frame or kit, you'll need to have some basic tools handy to cut and drill the frame itself. Since the frame's made from polymer, it's relatively easy to complete without any heavy-duty equipment like you would normally need for a metal 80% lower:

  • Hammer
  • Hand drill
  • Tabletop vise
  • Roll pin punches
  • Files or sandpaper
  • Dremel and snips

A pair of small, sharp snips work perfectly for cutting the excess material off the slide rails, while a small Dremel works just as well for cutting the barrel block to shape. Let's dive into the instructions and see what you need to do to get the frame completed and ready for assembly.

Note: Polymer80 used to include an end mill bit with this kit, though it has been found by most builders (and the manufacturer) that completing the frame with the tools listed above are easier. That means no end mill bit, and no need for a mill or heavy machinery.

Manufacturer's Warning: Drill the pin holes using the jig and hand drill with a drill press vise. DO NOT use a drill press either with or without a drill press vise or cross slide vise to drill your holes. Testing has shown while using a drill press, the bit will not self-center in the jig and will result in poorly placed or irregular pin holes.


How to Cut and Drill the P80 Frame

No matter which frame or pistol kit you buy, the steps below are all the same.  Click here to download a .PDF version of the instructions for your frame's model.

  1. Drill the trigger pin hole
  2. Drill the locking block pin hole
  3. Drill the trigger housing pin hole
  4. Cut the slide rails
  5. Cut the barrel block

Step 1: Secure the 80% Frame and Jig

The P80 frame snaps into place between the two halves of the jig. The jig is molded from polymer and may have some rough edges that require light sanding to ensure a clean fit. Taping the jig near the front and rear will help keep the assembly together when it's not clamped down in your vise.

The areas highlighted in green are the locations that need to be cut for the slide and barrel. The top rails can be snipped off and then sanded lightly to remove burs. The green "U"-shaped area filling in the barrel block is best removed using a Dremel, though a round hand file can be used, too.

Before cutting these areas down, we're going to drill the two pin holes on the frame, first. 

Step 2: Drill Pin Holes With Vise & Hand Drill

For this step, the jig and frame should be secured in your vise flat against the tabletop. Don't over-tighten the vise, or the jig will warp. Do not attempt to secure the jig upright, or the vise will also cause the jig to warp while drilling, ruining the frame.

You need to drill two holes -- the trigger mechanism housing pin hole, and the trigger pin hole -- through the frame. Again, do not attempt to use a drill press. Both holes on the jig are marked "M3" and "M4" for each drill bit.

  • Use the M3 drill bit for the trigger mechanism housing hole at the rear.
  • Use the M4 drill bit for the trigger pin hole above the trigger well.

A simple hand drill works fine for these holes. Go slow, and ensure the drill and bit are vertical when going through the jig and frame.

Step 3: Cut the Top Rail Section

The top rails can be trimmed using snips, hand files, or a Dremel. The sections highlighted in green need to be cut down so they're perfectly flush with the top edge of the jig itself.

Do not remove any other raised material. Some other parts of the frame protrude higher than the edge of the jig. Leave these areas alone and only remove the green areas.Once snipped, hand filing may be necessary to achieve a smooth edge that's free of burs. 

Step 4: Cut the Barrel Block

This area requires attention to detail, as the barrel block features rounded corners and rests between frame material that should not be modified or reduced. To prep the frame and jig, orient the assembly vertically in your vise.

Only remove the area highlighted in green. Do not remove material highlighted in red.

This section can be completed with a Dremel and hand files, or a drill press and drill bit. We recommend the former, as the P80 kit no longer comes with a bit for this section per manufacturer testing and customer feedback. There is a relief edge to indicate the edge of the barrel block.Use this edge as an indicator to guide you while you remove the frame's material.

A best practice is to remove most of the material, then finish off the area with a 1/4" round file. This slower and more precise method of removing material will leave a smooth, rounded finish without risking removing too much material.

With the barrel block cut and sanded, your Polymer80 frame is complete! Now it's time to assemble the provided components so the rest of your parts can be installed.


Assembling the Completed Frame

If you purchased a complete pistol kit with internals and a full parts kit, you have everything required for these next steps. If not, you'll need a frame parts kit to install the rear rail module and pins provided with the frame.

Step 1: Install the Locking Block Rail System

The LBRS incorporates both the locking block and and slide rails. Installing the the LBRS requires the provided 2mm x 25mm pin included with your frame's kit. To tap the pin into place, you'll need a small hammer, preferably a brass-head or hard rubber gunsmithing hammer.

Drop the locking block rail system into the frame directly over top the trigger well. The LBRS should be angled forward as shown above. Ensure the pin holes in the block/rail and frame align, then gently tap the 25mm pin into the front hole until it is flush on both sides of the frame.

Step 2: Install Magazine Spring & Mag Catch/Release

First, grab the magazine catch spring and insert it into the cut-out in the magazine:

Next, insert the magazine catch/release button on the left side of the frame, through the square cut-out just behind the trigger guard. The catch/release button has a small indent where the end of the spring will rest:

To make this step easier, it helps to have a small flat-head screwdriver or thin, long blade. Gently pull the spring away from the wall of the magazine well while inserting the catch/release button so the end of the spring can be inserted into the indent on the button once fully seated.

Step 3: Install Slide Lock Lever and Spring

While factory Glocks use a piece of spring steel, the P80 frame uses a coil spring for the slide lock, included with the kit. First, drop the coil spring into the pre-drilled hole in the center of the slide lock area:

Next, use a small punch or nail to compress the coil spring into the bottom of the slot:

With the coil spring compressed, you can insert the slide lock lever from the opposite side of the frame. The lip located atop the lever should be facing toward the rear of the frame. Simultaneously push the lever into place over top the punch or nail while moving the punch or nail away to allow the indented bottom at the center of the lever to capture the coil spring while seating the lever in the frame fully.

Step 4: Install Trigger Assembly with Rear Rail Module

Collect the trigger, trigger bar, trigger mechanism housing, rear rail module (RRM), slide catch/release lever, and trigger pin. The trigger, bar, housing, and RRM can be dropped into the top of the frame as one unit:

With the assembly dropped into the frame, the slide catch/release lever can be slid into the frame on the left-hand side of the trigger assembly. The hole in the lever should align with the holes in the frame and trigger for the trigger pin. With all holes aligned, the trigger pin can be inserted through the trigger pin ("M4") hole. Lastly, the trigger mechanism housing pin can be inserted in the "M4" hole drilled earlier at the rear of the grip.

At this point, your pistol is ready to be assembled with your barrel and slide of choice, and function-checked with an empty magazine and empty chamber. If you ran into any issues during fitment or install, see the troubleshooting section below.


Troubleshooting

While installing the slide or real rail module, you may find some components have a tight fit. Upon the first function test, you might find the slide binds up or fails to go into full battery. Simply racking the slide repeatedly may be sufficient to "work in" these new components. 

Tight Slide? Polish the Rails

If the slide is excessively tight and racking the slide is difficult, use some very fine-grit sandpaper to lightly polish the slide rails and top edges of the frame. Apply lubricant to the internals and slide, too. 

Tight-Fitting Rear Rail Module

Installing the RRM and trigger assembly can be a tight fit. Lightly polishing the inside of the frame may be required. Follow the steps below to assist with installation:

  1. Ensure all parts are fully seated and held secure during installation of pins.
  2. Attempt to install pin normally from one side with all parts (frame/RRM/trigger housing).
  3. Attempt to install pin normally from other side with all parts (frame/RRM/trigger housing).
  4. Attempt to install pin while using second pin for alignment from opposite side with all parts (frame/RRM/trigger
  5. housing).
  6. Attempt to install pin without trigger housing (This will allow the pin to “set” the RRM in the frame without the
  7. constraint of aligning the trigger housing).
  8. Re-attempt installation of pin normally or while using alignment pin from opposite side with all parts
  9. (frame/RRM/trigger housing).

If the rail module and pins cannot be installed with no trigger mechanism installed, do the following:

  1. Take the RRM out of the frame. Take the small M3 drill bit (Installed on your drill), push all the way through and pull out of the RRM to clean up the holes. DO NOT re-drill your frame at this point. You can clean up your holes with a deburr tool and lightly wet sand the holes without enlarging the holes.
  2. Attempt re-installation of all parts put together.
  3. If the plating on the RRM starts to chip and come off during this process it normally will not affecting the guns performance, you can lightly sand the area and remove the rest of the plating. Removing the plating does not affect the structural integrity

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.