Optics-Ready Slides 101

One of the most common questions our team gets on a regular basis is "Will my _____ optic fit on my _____ slide?" It seems like an easy one... but with how frequently new optics have been released on the market these days with varying housing dimensions, there is a ton of variables to consider. So we thought we would break down our optic cuts that we put on our GGP aftermarket pistol slides, and perhaps save one of your from sliding into our DM's with the same question. Let's begin!

GGP Slides

Before we dive into the nitty gritty, here's a quick recap on how GGP slides are milled for MRDS Optics (Micro Reflex/Red Dot Sight).

• GGP slides are milled forward of the rear sight dovetail with a sunken 'footprint' that snugly fits an optic without needing an adaptor plate (and thus raising the optic higher from the bore axis and introducing more failure points)
• Although our footprints are milled with extremely tight tolerances (+/- 0.003") any two of the same optic can have a variance in size larger than that, either longer or shorter. We chose to mill our final dimension to the median of this manufacturing variance, so the average optic will drop into our footprint snugly without excessive force. However, it's not uncommon to have an MRDS from any company that is over our +/- 0.003" tolerance and doesn't seem to fit. The solution is to handfit the optic into our footprint by removing an extremely small amount of material from the optic or slide in the rear wall of the footprint.
• The footprint is drilled and tapped for certain common screw lengths and thread pitches. Currently our service size slides (G19, G17, G26, P320) have two sets of threaded holes to accommodate multiple optic footprints in one. Our subcompact slides (G43/G43x, P365) only have one pair of threaded holes.
• The latest generation of GGP slides with more than one set of threaded holes will include a very thin shim plate to properly fit different optics in our footprint. The shim plates are engraved with the name of the corresponding optic, so the shim plate engraved with "RMR" must be used to fit a Trijicon RMR (or other RMR-footprinted red dot sights) whereas the shim plate engraved with "ROMEO1" is used to fit the Sig Romeo1.
• The shim plate isn't used when either the Leupold Deltapoint Pro or Sig Romeo Pro optics are used, because our footprint is cut to fit their overall longer length.
• A custom cover plate made from G10 is included for use when an optic isn't installed.
• Our subcompact slides (G43/G43x, P365) have a footprint milled for the Shield RMS-C and Sig RomeoZero. They also include a smaller G10 cover plate.
• The sunken footprint design allows the optic to sit lower on the slide and withstand recoil forces better than if riding on an adaptor plate. - even with a shim plate used. This means absolute cowitnessing iron sights is guaranteed when suppressor height sights are used, and lower cowitnessing can be achieved with certain other height iron sights.
• Because of the sunken footprint, the screws that came with your optic are more than likely too long, and will impede the inner parts of the slide if used.

Custom Screws

Every GGP slide comes with custom screws that we supply specifically for use with our slides because our sunken footprint reduces the depth of the screw holes. If you were to try and use the screws that came with your MRDS optic, chances are they are too long and will bottom out against internal parts like the extractor plunger rod. If you own or are servicing a pistol with an optic mounted GGP slide that is having extractor or ejection issues, the most common culprit to look at is the screws used to mount the optic. If a screw is too long, particularly on the right side of the slide, the screw will impede the extractor plunger hole or bind the plunger if it is installed. An easy way to check this is to strip the slide and install the optic with the screws. If you can visually see the right screw protruding into the extractor plunger channel, it needs to be replaced with a shorter screw.

Tolerances, Tolerances, Tolerances

Did you know what two identical MRDS optics from the same brand can vary in footprint length by as much as 0.01" (+/- 0.005) depending on how they are manufactured?

More Frequently Asked Questions

I have a ___ handgun, can you mill it for an optic and/or add serrations?

• No, unfortunately we will not. We could, but with the time and cost associated with retooling, recalibrating and reconfiguring our machines that are setup for pumping out GGP slides and precision parts... you wouldn't want to see that bill! 
• There are hundreds of competent gunsmiths and machine shops that offer these services at a competitive price point because they are setup to do it.
• Considering when you buy a GGP aftermarket slide you not only get a hybrid optic cut footprint, cover plate, shim plates, tighter critical tolerances (you can't reliably add material to a slide once its been milled away) a high quality finish/coating AND a lifetime warranty... you may want to consider leaving your slide unmodified and getting an aftermarket slide instead.

What iron sights do I need to get? Which sights will co-witness with my optic?

• There are many pistol sight manufacturers that produce high quality parts that we consider 'good-to-go' with Trijicon and Night Fision being the first brands we recommend to customers.
• Something to consider when ordering iron sights is the amount of overhang some rear sights have, depending on the brand. If you wish to install a red dot or reflex optic, the rear sight body cannot protrude over the milled optic footprint.
• To achieve an absolute co-witness with an optic (the reticle will be very close to the top front sight post when centered) both front and rear sights will need to be tall. This is often called "suppressor height" and for most shooters this will be satisfactory for defensive pistol use. Keep in mind that depending on the model of MRDS you are using, the height at which the centered reticle sits above the top of the slide can vary by a tenth of an inch or more. It's best to measure the exact height desired and order. For those who want a lower third co-witness, this is also the case that is best. Determine what is your desired iron sight height by measuring off the top of the slide, and order accordingly. We recommend Dawson Precision for ordering custom height iron sights.