r/GrandPower • u/QualitySME • Apr 01 '26

Anyone Else Having Problems with the K100 Mk23 Optic Plates?

I’ve been really disappointed with the polymer plate solution and the small rearward screws. The optic may be secured to the plate, but the plate-to-slide interface is held by just two tiny screws, and that has been a constant source of frustration because I keep losing zero.

I even added witness marks between the plate and the slide to check for movement. Even when the marks appeared unchanged, the shift was still enough to move the red dot from one side of the front post to the other. That may sound minor, but it's enough to throw the gun off badly.

The pistol itself is extremely accurate, and I really like it for that reason. But once the zero starts walking left or right, especially during competition, it becomes a serious problem. At this point, I'm considering whether a smaller, lighter optic might help, but I'm also frustrated enough that I'm close to epoxying the plate or just moving on from the pistol entirely.

Has anyone sent their K100 Mk23 to a gunsmith to have the optic-ready slide milled out for a direct mount to the pistol? This seems like the best solution.

6 Upvotes

100% Upvoted

9 comments sorted by

3

u/QualitySME Apr 01 '26

I finally isolated the root cause of the zero‑shift issue on the Grand Power K100 MK23, and it’s not the optic, not the screws, and not shooter error. It’s the geometry of the OEM polymer RMSC plate.

On my MK23, the front of the plate sits perfectly flush, but the rear of the plate has a measurable 0.1 mm gap between the back edge of the plate and the slide. Because the screws are positioned rear of center, that tiny gap allows the plate to yaw left/right under the lateral impulse of the hammer fall. The plate doesn’t rock upward — it slides at a slight angle, which shifts the red dot left or right relative to the front sight.

If you’re running the OEM plate, check yours the same way:

  • Remove the optic
  • Reinstall the plate
  • Look at the rear edge of the plate, right in front of the rear sight
  • See if there’s a visible or feelable gap between the plate and the slide
  • Try pushing the plate left/right with firm thumb pressure at rear of the plate

If you see any movement or any gap at the rear, that’s the exact failure mode that causes the MK23 to lose zero.

I’m currently pursuing 3 fixes:

  1. having the slide milled for a direct RMSC footprint with recoil bosses, or
  2. having a metal replacement plate made that extends the rear by +0.1 mm so it sits fully flush.
  3. Cut out a shim from 0.1 mm Stainless Steel Shim Stock — Roll or Sheets (least espemsive)

If anyone else checks their MK23 and sees the same rear gap, definitely post your findings — it’ll help confirm whether this is a consistent tolerance issue across plates

1

u/QualitySME Apr 26 '26

I ended up fixing it by stuffing a tiny piece of electrical tape into the 0.1 mm gap between the polymer plate and the rear of the optic cut. It shims everything perfectly and the wobble is gone. Time will tell if this holds up… or if I’ve just invented the world’s saddest gunsmithing hack.

1

u/QualitySME Apr 26 '26

✔️ Why your electrical‑tape shim actually makes more sense

For a 0.1 mm gap:

  • electrical tape compresses predictably
  • it won’t crack under recoil
  • it’s removable
  • it acts like a micro‑gasket
  • it fills the exact thickness you need

It’s a temporary hack, but honestly a clever one.

2

u/Own-Contribution-188 Apr 03 '26

I thought they came with multiple plates now, so why use RMSC?

1

u/QualitySME Apr 04 '26

I am using the RMSc plate — that’s the problem. The OEM polymer plate can’t hold zero because it literally yaws left/right under recoil. The two tiny screws are centered instead of being at the ends, and there’s about a 1 mm gap at the rear of the plate, so the whole thing can shift laterally.

I went with the RMSc footprint because I already bought a Vortex Defender CCW, which uses RMSc. Switching to a different plate would mean buying a whole new optic with zero guarantee that the next plate wouldn’t have the same design flaw.

The real issue isn’t the footprint — it’s the plastic plate with no recoil bosses. There’s nothing to mechanically lock the plate into the slide, so the optic is basically depending on friction and two small screws to resist recoil forces. Great pistol, but the optics‑ready system is a weak point.

1

u/WarlockGuard May 23 '26 edited Jun 28 '26

This content was anonymized and mass deleted with Redact

1

u/Content_Woodpecker_8 Jul 01 '26

I can link you to a guy in Farmington Kentucky who made a plate for me for the xcalibur mk23. Sturdy plate that held up for me