Polymer80 PF45 80% Large Frame and Jig Kit — Glock 20 (10mm) and Glock 21 (.45 ACP) Compatible

Description

Polymer80 PF45: The 80% Large Frame Kit for Maximum Caliber Builds

Stop settling for factory limitations. The Polymer80 PF45 80% Large Frame and Jig Kit puts you in the driver’s seat for building a .45 ACP or 10mm Auto pistol exactly the way you want it. Designed around Glock 20 and Glock 21 Gen 3 component geometry, the PF45 gives you the wide-body large-frame format that handles the most powerful semi-auto pistol calibers commonly available.

Americans Gun carries the full Polymer80 ecosystem. Pair the PF45 with components from our Frames and Jigs section or browse our PF940v2 full-size 9mm kit if you’re building in the standard calibers. For large-frame builders, the PF45 stands alone in the Polymer80 lineup.

Engineering Behind the PF45

Polymer80 engineered the PF45 to address two core challenges in large-frame pistol building: structural rigidity under 10mm Auto pressures and ergonomic grip design for larger hands and heavier slides.

The frame uses Polymer80’s proprietary reinforced polymer composite — a fiberglass-infused thermoplastic that’s significantly stronger than standard polymer at elevated temperatures and under sustained firing stress. The locking block recess features additional reinforcement compared to the compact frame variants. The result is a frame blank that holds up to extended range sessions with full-power 10mm loads that factory polymer frames sometimes struggle with over time.

The grip design incorporates Polymer80’s signature enhanced texture panels and a more neutral grip angle (17 degrees vs. Glock’s 22 degrees), which many shooters find naturally aligns the pistol with their wrist for faster target acquisition. The undercut trigger guard allows a higher grip, reducing muzzle flip under recoil.

Also available: PF940Cv1 compact kit and PF9SS single-stack kit.

What’s In the Box

• PF45 80% large frame blank (Black, FDE, OD Green, or Gray)
• Billet aluminum top jig plate
• Billet aluminum bottom jig plate
• Drill bit set — fire control group holes
• End mill bit — rear rail/locking block area
• Hardware pack with all fasteners and alignment pins
• Step-by-step illustrated instruction guide

Technical Specifications

Spec	Value
Manufacturer	Polymer80, Inc.
Model	PF45
Frame Completion	80% — machining required
Platform Compatibility	Glock Gen 3 G20 / G21
Calibers Supported	10mm Auto, .45 ACP, .40 Super
Frame Class	Large Frame (wide body)
Slide Length	4.61″ (G20/G21 standard)
Material	Fiberglass-reinforced polymer composite
Grip Angle	17 degrees (Polymer80 ergonomic)
Trigger Guard	Undercut for high grip
Accessory Rail	Picatinny integrated (4 slots)
Jig Material	Billet 6061-T6 aluminum
Made in USA	Yes

Parts Needed to Complete Your PF45 Build

After machining the frame, you’ll need to source and install:

• Slide Assembly: Glock 20 or G21 compatible 4.61″ slide — bare or assembled
• Barrel: 10mm Auto or .45 ACP G20/G21 compatible drop-in barrel
• Rear Rail Module: PF45-specific RRM (different from compact/full-size PF940 RRM)
• Locking Block: Large frame Gen 3 locking block
• Lower Parts Kit: Glock Gen 3 large frame LPK (trigger assembly, magazine release, slide lock, etc.)
• Magazines: Glock 20 or Glock 21 double-stack magazines
• Sights: Front and rear sight set compatible with your slide

Pro tip: Order the PF45-specific rear rail module and frame pin kit at the same time to have everything on hand for the build. Also grab our PF940V2 jig kit for reference on the jig process.

10mm vs. .45 ACP — Which Should You Build?

The PF45 platform handles both calibers, and the choice comes down to your end use:

10mm Auto is the power choice. Factory 10mm loads push a 180-grain bullet at 1,300 fps for 676 ft-lbs of muzzle energy. For hunting pistol use, bear country hiking, or those who want the most powerful 9mm-footprint pistol available, 10mm is hard to beat. Recoil is significant but manageable on the heavy G20-sized platform.

.45 ACP is the proven fight-stopper. With a 230-grain bullet at 830–900 fps, .45 ACP remains one of the most effective defensive cartridges in the world by wound ballistics data. It’s also somewhat cheaper to practice with than 10mm, and the recoil impulse is more of a push than the sharper snap of 10mm.

Pros and Cons

Advantages:

• Large-frame platform — only Polymer80 option for .45 ACP and 10mm builders
• Reinforced polymer composite rated for sustained 10mm Auto fire
• Ergonomic improvements over factory Glock — better grip angle, undercut guard
• All-inclusive jig kit — nothing extra to buy for machining
• Enormous G20/G21 aftermarket component selection
• Made in the USA

Considerations:

• Machining required — not finished at purchase
• Large frame size — not ideal for concealed carry applications
• PF45-specific RRM required (separate purchase)
• State laws on 80% frames vary significantly

Important Legal Notice

The PF45 is an 80% pistol frame — an unfinished component that is not classified as a firearm under federal law. It can be shipped without FFL transfer at the federal level. State and local laws vary greatly, and several jurisdictions have enacted regulations that restrict or prohibit the purchase, possession, or completion of 80% frames and unserialized firearms. Buyers are fully responsible for ensuring compliance with all applicable laws in their jurisdiction before ordering. Americans Gun does not provide legal advice.

Frequently Asked Questions

Q: Can I use aftermarket 10mm slides with the PF45?

A: Yes. Any G20-footprint compatible aftermarket slide in the 4.61″ length will work with the PF45. Companies like Zev Technologies, Agency Arms, and Brownells all produce or have produced G20-compatible slides. When selecting a slide, confirm it’s listed as Glock 20 Gen 3 compatible to ensure correct fit with the frame’s rail geometry.

Q: What drill press specifications do I need?

A: Any bench-top or floor-standing drill press with variable speed and the ability to accept the supplied drill bit sizes (typically 3mm and 4mm) will work. The jig includes top and bottom plates that clamp firmly to the frame blank and provide positive stops for all drilling operations. Many builders also use milling machines for cleaner results, but a drill press is fully sufficient for completing the frame correctly.

Q: Is the PF45 large frame grip suitable for smaller hands?

A: The G20/G21 grip is wide — noticeably wider than a G19 or G17. Shooters with average-to-large hands typically find it comfortable. Those with smaller hands may find the grip stretch challenging. Polymer80’s enhanced grip texture improves control even with a marginal grip size. If grip size is a concern, handle a factory G21 before ordering to gauge comfort.

Q: Does the PF45 come with any warranty?

A: Polymer80 backs the PF45 frame blank with a limited lifetime warranty covering manufacturing defects in materials and workmanship. User machining and completion work are not covered, nor are damages from improper completion, incorrect component use, or unauthorized modifications. Retain your purchase receipt for warranty service.

Q: Can I install a compensator on a PF45 build?

A: Yes. Select a threaded barrel for your caliber choice and fit a compatible compensator. The PF45’s Picatinny accessory rail allows mounting a weapon light or laser alongside a compensator. Verify that the compensator extends within the slide’s window clearance if you plan to run a compensated barrel inside a ported slide configuration.

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