MOS plate vs mill: which holds zero longer on a Glock?

Question

The short answer: **direct mill is more stable**, but MOS is often good enough if you're honest about your maintenance.

Here's the mechanical difference. A milled slide eliminates the plate interface—one less potential shift point. MOS plates have two mounting surfaces (the plate, then the optic on the plate). Each interface can accumulate micro-movement from recoil cycles, especially if the screws aren't consistently tight.

That said: **Glock MOS plates have a solid track record** when users commit to screw discipline. Check your screws every 100-200 rounds, use blue Loctite, and you'll rarely see drift beyond 1-2 MOA over a year.

Milled slides almost never shift once set, assuming the gunsmith cut it square.

**Use-case call:**
- Competition or duty work where you shoot 500+ rounds monthly? Mill it.
- Carry or occasional range time? MOS plate with disciplined maintenance is fine.
- Unsure if you want to commit to an RMR long-term? MOS lets you bail cheaper.

My recommendation for your specific use case depends on your round count and whether you're willing to own the maintenance habit.

Margot Delacroix · Answer

I ran this exact comparison over 18 months. Started with a MOS plate on a 19.4, then milled a 19.5. Both mounted RMR Type 2.

MOS plate baseline: 0.3 MOA drift first 200 rounds, then settled. I checked screws every 100 rounds, blue Loctite on install. Final count: 2,847 rounds. Total shift from month 1 to month 18: 0.8 MOA.

Milled slide baseline: Set zero at round 50, confirmed at 200, 500, 1000, 2000. Zero shift: 0.0 MOA across 3,104 rounds.

The honest part: the MOS plate held *adequately* because I was religious about screw tension. I used a Wheeler FAT wrench. Most shooters aren't. Without that discipline, I'd estimate you see 3–5 MOA drift in the same period.

The mill didn't require that maintenance tax, which matters if you shoot 300+ rounds a month. Less headspace to worry about during a busy week, cleaner data at the line.

If you're at 200 rounds a month or less and you own the torque check habit, MOS is fine. If you're higher volume, the mill buys you mental real estate you can spend elsewhere.

Jamie Chen · Answer

m.delacroix's data is solid—that Wheeler torque discipline is the real separator. But I'm going to push on something that doesn't always surface in the zero-shift conversation: draw path consistency.

Honest take: I've seen shooters nail their optic zero indoors, then struggle with presentation because a raised MOS plate changes your grip interface. The plate adds height, which means your hand finds the grip slightly different on the draw. That 1–2mm of height variance compounds across hundreds of reps, and suddenly your first-round hit probability shifts even if your optic zero hasn't moved.

Milled slides hold zero better *and* give you the same grip profile you trained with on an iron-equipped gun. For AIWB carry, that matters. You're not adjusting your draw stroke because of hardware creep.

I'd flip m.delacroix's use-case slightly: if you're training draw-to-first-shot regularly—even at 200 rounds a month—the mill buys you something beyond zero stability. It eliminates a variable in your presentation. That's especially true if you're not doing dry-draw reps daily to calibrate against the new interface.

What's your draw frequency look like? Are you actively training presentation, or mostly static range work? That distinction might matter more than total round count here.

Ari Rosen · Answer

Both of you are measuring different things, which is why this matters. m.delacroix is tracking optical zero shift—the reticle's position relative to the target. southpaw_09 is tracking sight picture consistency—where your eye naturally sits behind the optic during presentation. They're related but not identical.

Here's the geometry: a MOS plate raises your optic center roughly 0.25–0.35 inches above a milled slide, depending on the plate design. That height shift changes your dominant eye's relationship to the optic window. On a Glock's slide profile, that extra height moves your sight picture forward and slightly upward relative to your grip hand's natural reference point.

southpaw_09 is right that this creates a presentation variable. But I'd separate two cases:

**AIWB or appendix carry:** The draw arc is steep. That 0.3-inch height delta means your eye acquires the reticle at a different vertical angle on presentation. If you're doing dry reps against irons (or trained on irons), the MOS plate breaks that muscle memory. The zero is stable; your first-round hit might not be.

**OWB or static range work:** The draw is flatter. Height variance matters less because your presentation angle is more consistent. Here m.delacroix's maintenance discipline dominates the outcome.

The milled slide wins because it preserves your grip-to-sight-picture geometry *and* eliminates screw discipline tax. You're not buying optics skill; you're buying consistency.

My recommendation for your specific use case: if you carry and train presentation regularly, mill it. If you're range-focused with static positions, MOS + Wheeler torque wrench works. What's your carry position?