RMR vs EPS for EDC—which one actually fits your holster?

Question

The housing difference matters more than the spec sheet suggests.

The **RMR Type 2 is larger**—it sits higher and extends further back on the slide. The **EPS is more compact** in both directions. On paper that sounds like the EPS wins. It doesn't always.

Here's what actually matters for holster fit:

1. **Your holster was probably built for one or the other.** If it's molded for an RMR and you drop an EPS in, you lose retention where it counts—the trigger guard area. The opposite is worse: an EPS holster with an RMR leaves you with a loose fit at the rear.

2. **Kydex retention depends on contact points.** A proper AIWB holster locks the gun in place with pressure on the trigger guard, the muzzle, and ideally a grip shelf. The optic housing shouldn't be doing the work, but when the housing is *undersized* for the mold, you've got a gap that makes the gun shift.

3. **The RMR's height can actually be an advantage** if your holster was designed for it. You get more consistent seating.

Where the EPS wins: If you're using a universal or adjustable holster (Phlster, certain Tenicor models with adjustable retention), the smaller footprint gives you more flexibility to swap guns and optics without remolding.

**My concrete recommendation:** Before you buy the EPS, confirm your holster maker supports it specifically. If they don't have a tested setup, you're not buying a gun sight—you're buying a problem. Call the holster maker. Ask them directly: "Do you have this mold dialed for EPS, or do I need RMR compatibility?" That answer matters more than the optic's feature list.

What holster are you running?

Ari Rosen · Accepted Answer

The retention point analysis is solid, but the optic window and housing geometry deserves more specificity here because it actually drives the holster fit problem you're describing.

RMR Type 2: 26.3mm length, 27.8mm width, 13.5mm from center optic window to rear of housing.

EPS: 24.8mm length, 26.3mm width, 11.1mm from center optic window to rear of housing.

That 2.4mm rear-pocket difference is the real culprit. When a Kydex mold is built around the RMR's rear projection, the EPS doesn't occupy that rear volume—the gun can shift backward in the holster because the retention shelf at the grip/trigger guard area now has extra space behind the slide to travel into. It's not about optic-to-trigger guard contact; it's about the *overall slide-to-holster envelope*. The optic housing is just the most obvious dimension that changed.

Where this gets critical: The window height matters too. RMR sits at 8.1mm above the slide plane; EPS at 7.6mm. If your holster was molded assuming that 8.1mm sight-line relationship, an EPS creates a slightly different angle-of-repose for the gun in the kydex channel. Not catastrophic, but measurable.

Your core point stands—ask the maker which platform they dimensioned for. But the *why* is the optic window height and rear housing projection, not retention zones. The housing *is* the problem, geometrically speaking.

My recommendation for your specific use case: Get the exact mold generation from your holster maker (some iterate these). Then cross-reference against their documented compatibility list. Don't assume universal.

Tom Lassiter · Answer

Both of you nailed the geometry—that 2.4mm rear projection and the window height difference are exactly what I see failing in the field. The draw-path clearance point is real too; I've watched shooters fight their own holster because the optic envelope changed and they didn't realize it.

Here's where the manufacturer support question matters: Most holster makers don't iterate both platforms natively. They pick one, build the mold around it, and call it compatible with "RMR-footprint optics" or "EPS-compatible." That language is doing heavy lifting.

The makers I trust to have actually tested both:

**Phlster** – They publish their mold generations publicly. Their Floodlight AIWB comes in documented RMR and EPS versions. Different kydex channels. You order the right one; they've handled the envelope math.

**Tenicor** – Their Certum3 has adjustable retention that genuinely accommodates both, but only if you dial the clamping force correctly. Call them; they'll walk you through the fit-check.

**Legacy Firearms Co** – RMR-first shop, but they've tested EPS on specific molds. They'll tell you which generation works.

Where EPS wins: If you're rotating between multiple guns and holsters, the smaller footprint means fewer holster SKUs. But that only works if each holster is built for EPS specifically.

For a single-gun setup? Call your holster maker with your gun model and optic. Don't assume universal compatibility. They either have tested data or they don't.

Jamie Chen · Answer

Good specs, and honest—that 2.4mm rear projection difference is exactly the kind of dimension that doesn't sound like much until your gun moves a quarter-inch in the holster during the draw. frm42 is right on the geometry.

I want to layer in something I see constantly with AIWB that compounds this: the draw path. An RMR sits taller, which means your grip hand clears the optic housing on the way up with a certain arc. Drop an EPS in an RMR-molded AIWB and you've got less vertical real estate above the sight. It changes your natural draw angle slightly—your thumb or grip might catch the housing on a press-out draw if your holster wasn't dimensioned for that lower window height.

The reverse is worse: EPS holster, RMR optic, and now you've got extra clearance above the slide. Sounds fine until you realize your retention was built around occupying that space. You're re-learning your draw stroke on a gun that's now sitting differently in the waistband.

I've seen this trip up shooters who swap between two guns with different optics and use the same holster. One draw feels locked; the next one feels sloppy. They blame the holster or the gun. It's usually the optic-to-holster envelope mismatch.

So the question for you: are you looking to run the same holster between two guns with different optics, or is this a single-gun, single-holster decision? That answer changes whether the geometry matters as a hard blocker or just a comfort thing.