Slides and barrels for Polymer80 frames: what fits what

A finished Polymer80 frame takes the same slides and barrels as the Gen 3 Glock it copies. That sounds simple until you are looking at a slide listing that says "G19 Gen 3/4" and a barrel that says "G19 Gen 5". Here is how to read them.

Slide generation matters more than brand

Any Gen 3 pattern slide works on a PF940C, PF940v2, PF940SC or PF45, whether it is a factory Glock slide, a Polymer80 PFC9 or PFS9 assembly, or an aftermarket cut. "Gen 3/4" slides are fine: the frame difference between those generations is in the recoil spring seat, not the slide rails. Gen 5 slides have a different front cut and will not run on a PF940 frame.

Barrels

Barrel generation follows the slide. A Gen 3 or Gen 3/4 barrel fits a Gen 3 slide. Threaded barrels are longer by the thread length only and change nothing about fit. The PF45 takes G20 (10 mm) or G21 (.45 ACP) barrels and the matching slide; do not mix them.

Complete slide assemblies

The fastest route is a complete assembly: slide, barrel, striker, extractor, sights and guide rod already fitted. Polymer80 sells them as PFC9 (compact, for PF940C) and PFS9 (full-size, for PF940v2). Aftermarket completes work the same way; check the listing names the Gen 3 model.

The parts kit

Lower parts kits are also by model: a G19 LPK for the PF940C, G17 for the PF940v2, G26 for the PF940SC, G43 for the PF9SS, G21 for the PF45. The kit supplies the trigger, connector, locking block, slide stop, magazine catch and pins that the frame kit leaves out.