Legion Precision // Build Education

Does a Glock 19 Gen 3 MOS Slide Fit Your Polymer80 or PSA Dagger Build?

By Carl Woodard

Short answer: yes. A genuine Glock 19 Gen 3 MOS slide (part #79008) is one of the most common OEM slides used to finish a Polymer80 PF940C build, and it will run on a PSA Dagger frame spec'd to Gen 3 dimensions. Confirm your frame's slide-stop and rail spec first, because that, not the slide, is where fitment problems usually start.

#79008Glock part no.
Gen 3Only generation
MOSOptic-ready cut
OEMGenuine Glock

// 01What You Actually Get

This is a factory Glock spare slide, not a complete upper. Straight from Glock, the package includes:

  • GLOCK MOS slide with assembled internals
  • GLOCK MOS cover plate
  • GLOCK standard sights
Not included, and required to finish a working build: barrel, recoil spring assembly, and the MOS adapter plate for your optic. Several listings use the word "complete" loosely. If you have a spare Glock 19 Gen 3 barrel and recoil assembly, they drop straight in. If not, budget for them.

// 02Platform-by-Platform Fitment

OEM Glock 19 Gen 3

Direct fit. This is the frame the slide is made for. Add a barrel and recoil assembly, mount your optic with the correct MOS plate, and you're done.

Polymer80 PF940C

The PF940C is a Glock 19 Gen 3-pattern frame, and #79008 is a popular slide to finish one. Verify your slide-stop lever and rail spec, then hand-cycle and check lockup before live fire.

PSA Dagger

The Dagger is broadly Glock 19-pattern, but confirm your Dagger's generation and slide spec before ordering. Verify rail and slide-stop fit rather than assuming.

Not compatible: Glock 19 Gen 4 and Gen 5 frames. This is a Gen 3 slide only.

// 03Quick Compatibility Reference

FrameFits #79008?Before you install
Glock 19 Gen 3 (OEM)Yes, directAdd barrel, recoil, optic plate
Polymer80 PF940CYes, commonVerify slide-stop and rail spec
PSA DaggerVerify firstConfirm generation and slide spec
Glock 19 Gen 4 / Gen 5NoNot compatible

// 04Mounting a Red Dot

The MOS cut doesn't take an optic directly. It uses a plate matched to your optic's footprint, such as RMR, Holosun 507C, DeltaPoint Pro, or Vortex Venom. Choose the plate for your optic and torque the screws to spec so you don't strip a screw or lose zero.

Tip: plates are sold separately. Order the right one with the slide so your build isn't stuck waiting on a part.

// 05Where to Buy a Genuine OEM Slide

Aftermarket "OEM-style" slides are everywhere; a genuine Glock factory slide is what keeps factory reliability. Legion Precision Weapon Systems stocks the genuine Glock 19 Gen 3 MOS slide (#79008), ships fast from a veteran-owned 07 FFL / 02 SOT, and can pair it with the barrel and recoil parts you need, plus optic cuts and Cerakote from our in-house shop.

Shop the #79008 SlideAsk About a Barrel

// 06FAQ

Does the #79008 slide include the barrel?

No. It ships with assembled internals, the MOS cover plate, and standard sights. The barrel and recoil spring assembly are sold separately.

Will it fit a Gen 4 or Gen 5 Glock 19?

No. It's a Gen 3 slide only.

Do I need an adapter plate for my optic?

Yes. The MOS cut needs the plate that matches your optic's footprint; plates are sold separately.

Can I use my existing Gen 3 barrel and recoil spring?

Yes, if they're from a Glock 19 Gen 3. Otherwise you'll need to add them.

LEGION PRECISION WEAPON SYSTEMS // SEGUIN, TX // VETERAN-OWNED
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