Polymer80 PF940C Jig Kit for PF940C Frame Blanks - polymer 80
Pros & cons
What works
- Provides +/- 0.003 inch rail alignment tolerance — critical for reliable slide cycling.
- Includes proprietary front and rear rail modules — avoids sourcing separate, often out-of-spec parts.
- Weighs 1.2 lbs — stable during drilling without being unwieldy.
- Three-piece jig design — allows for easy debris clearance during the milling process.
Trade-offs
- Plastic drill bushings wear after 2-3 uses — can introduce up to 0.5mm of bit wander if reused excessively.
- Does not include drill bits or end mill — adds $25-40 in required tooling cost.
- Locking block pin is a single, non-standard diameter — replacement requires ordering from Polymer80 directly if lost.
- Jig lacks positive indexing for the trigger pin hole — requires careful visual alignment before drilling.
Video review
Expert review
Specs at a glance
About this product
The Polymer80 PF940C Jig Kit is a precision-molded fixture designed to guide the drilling and milling operations required to complete an unfinished PF940C frame blank into a functional Glock 19-compatible receiver. This kit contains all the specialized tooling needed for the final 20% of machining on an 80% lower. Following the proper sequence with this jig transforms a raw polymer blank into a serialized or unserialized firearm component, depending on your jurisdiction's requirements.
What is the Polymer80 PF940C Jig Kit used for?
This jig kit is used to machine the critical fire control group pin holes and trigger housing channel in a PF940C 80% frame blank. The direct answer is that it provides the necessary alignment and containment for a handheld drill and router (or Dremel tool) to complete the frame. The front and rear rail modules are installed through the jig's alignment posts, which ensures the slide rails are parallel to the bore axis within a tolerance of +/- 0.003 inches. Without this jig, achieving reliable slide-to-frame fit and safe sear engagement is virtually impossible for a home builder.
How does the Polymer80 PF940C Jig Kit compare to the ModFuze LR-308 Jig?
The PF940C Jig is optimized for compact polymer pistol frames, while the ModFuze LR-308 Jig is designed for large-format rifle receivers. The direct answer is that the PF940C kit is simpler and faster to use, requiring about 45 minutes of active machining time versus 2+ hours for the LR-308. The LR-308 jig is more complex because it must manage the larger .308 platform and includes steel reinforcement inserts for the drill bushings, making it more durable for multiple uses. For a single pistol build, the PF940C kit is the more efficient choice.
What does it weigh and what are the dimensions?
The complete kit weighs 1.2 pounds (544 grams) and the assembled jig with frame blank measures 7.5 inches long, 5.25 inches tall, and 1.75 inches wide. The direct answer is that it's a compact, hand-held workholding fixture. These dimensions are critical because they must contain the frame blank while allowing clear access for a standard 3/8-inch drill chuck and a router base. The weight is sufficient to dampen vibration during drilling but light enough to clamp securely to a bench vise.
Who is this NOT for?
This jig kit is not for builders who lack basic mechanical aptitude or the required tools. The direct answer is it's not a complete solution—you must supply a drill, router, vise, and appropriate safety equipment. It is also unsuitable for builders in jurisdictions where completing an 80% frame is prohibited without serialization or manufacturer licensing. If you need a finished, ready-to-assemble frame, consider a pre-machined serialized frame instead of this DIY kit.
What's in the box?
The kit contains one injection-molded three-piece jig, one set of 3mm and 4mm drill bit guides (bushings), one front rail module, one rear rail module, and one locking block pin. The direct answer is that it includes the proprietary hardware for rail alignment but not the power tools. Notably, it does not include the drill bits or end mill; you must source those separately, and I recommend the specifications outlined in our drill bit technical guide.
Is the Polymer80 PF940C Jig Kit worth it at $50.99?
At $50.99, this jig kit is worth the cost if you plan to complete more than one PF940C frame blank. The direct answer is that it amortizes its value over multiple builds. As a single-use consumable for most builders (the plastic drill guides wear), the cost is justified by the precision it guarantees. Compared to the potential cost of ruining a $120 frame blank due to misaligned holes, this jig is a necessary and relatively inexpensive insurance policy for a successful build.
Key attributes
| Caliber | 9mm / .40 S&W / .357 SIG |
| Frame Compatibility | Glock 19 Gen 3 |
| Jig Material | Injection-molded polymer |
| Weight | 1.2 lb (544 g) |
| Dimensions | 7.5" L x 5.25" H x 1.75" W |
| Machining Time | 45-60 minutes |
| Includes Rails | Yes |
| Tool Requirements | Drill, Router, 3/8" & 1/4" bits |
Frequently asked questions
- Is it compatible with Gen 5 Glock parts?
- Yes, the PF940C frame is designed for Gen 3 Glock 19 parts compatibility. This includes slides, barrels, and most internal components from Gen 3. Some Gen 5 parts, like the ambidextrous slide stop, may require modification. Always verify fit with the specific parts kit from your vendor, such as Lone Wolf or Brownells.
- Does it fit standard Glock 19 holsters?
- A completed PF940C frame will fit most Glock 19 holsters, but not all. The trigger guard geometry and rail section can vary slightly. I recommend kydex holsters from Vedder or T-Rex Arms for the best retention. Test fit is advised; allow for a 1-2 week break-in period for rigid holsters.
- How long does the machining process take?
- The machining process takes approximately 45-60 minutes of active work with a drill and router. This does not include setup, tool changes, or cleanup. Drilling the three pin holes takes about 5 minutes. Milling the trigger pocket and channel is the most time-consuming step at 25-35 minutes with a steady hand.
- Can I use this jig on an aluminum 80% lower?
- No, this jig is specifically molded for the polymer PF940C frame blank. The drill bushings are designed for polymer and will deflect or break if used on aluminum. For aluminum pistol frames, you require a jig with hardened steel bushings, like those used for the 1911 platform.