Manufacturers are releasing new RDS (red dot sight) products at a fast and furious rate. Everything from new firearms, complete weapon systems, holsters and lights. Look into any gun store case and 30% of the pistols are equipped with RDS. If you’re feeling sight envy, this article is for you.
Custom RDS plates
With nearly every new firearm supporting RDS, there is a rich set of firearm/sight combinations, or should I say a hodge-podge? In a previous article, I stated that there is no standard for RDS mounting footprints, although the industry seems to be coalescing around a handful of more popular ones. That is until yet another new footprint is released. One issue is that several manufacturers of RDS patented their footprint and anyone who wants to use it needs to license the design – which has created some strange workarounds.
For example, many sights use the Trijicon RMR footprint, but there actually are two different footprints for this sight – one licensed and one a workaround. The Trijicon-licensed footprint has flush screw holes with separate machined bosses to take the recoil impact, while the Zev Technologies footprint has raised screw holes and no separate bosses.
While many manufacturers machine a sight-specific footprint into their slides, limiting your choices, Glock offers the infinitely flexible MOS (Modular Optic System) for its Gen 4 and up firearms. This system is designed around sight-specific adaptor plates. If Glock doesn’t make a plate for your sight, then the sight manufacturer or a third party might.
From top to bottom, figure 1 shows a Trijicon RMR next to an upside-down OEM Glock MOS plate and an aftermarket C&H Precision Weapons 509T MOS plate. The Glock MOS supports dozens of footprints just by changing the plate. Note the raised metal down the center of the slide cut and the small boss at the ejection port side of the cut (red arrow), which keeps the plate in place. Figure 2 is a close-up of this plate.
The aftermarket slide in the middle has flush-cut screw holes and 4 machined bosses to hold the optic in place. What optic? Good question and this site can help you figure that out. This slide is cut for the Docter/Noblex standard, and I bought it to mount a Vortex Viper.
At the bottom is a “Zev cut” Trijicon RMR slide with a fully-enclosed Holosun HE509T-RD X2 and the included mounting plate. The 509T is designed so that the optic is slid onto the plate from the side and locked into place. However, the plate is designed to fit the patented Trijicon footprint and not the ZEV cut footprint. In fact, the included plate won’t mount on the bottom slide because the screw hole bosses are too big for the holes in the plate for the plate to be mounted. Enlarging the holes doesn’t work because now that the plate fits flush, the optic won’t clear the screws.
This means that a 509T, or any other sight using the Trijicon RMR footprint, may or may not mount on your RMR-cut slide depending on which RMR cut was used. As of now, there is no way to mount a 509T on a Zev or Shadow Systems cut slide as no one makes an adaptor plate. After a bunch of phone calls to their support line from confused customers, Holosun now states this on the 509T product page.
Neither Glock nor Holosun makes a plate that will mount the 509T on a Glock MOS, but C&H Precision Weapons does (figure 3), along with dozens of other plates. You can think of them as an adoption agency, matching firearms with sights when the manufacturers don’t.
Tools
Along with the firearm, RDS and possibly a plate, you need a torque wrench and the specs for every screw you will be working with. The two traditional torque wrenches on top of figure 4 might be great for working on cars, motorcycles, and perhaps AR rifles, but they are not well-suited for working on pistol sights.
Pictured left to right are precision torque wrenches from Borka Tools, Fixit Sticks and Capri. The Capri is the highest precision and most expensive tool, but it might be what you want if you are a professional armorer. Before buying a torque wrench, determine the setting range you will need by looking at the firearm, plate and RDS torque specs.
There are two other important points: first, don’t reuse screws when a sight is removed. Since the screws are small and were torqued, they could be stretched, or the head might be ready to come off if they are retorqued. Second, use a non-permanent locking compound on your mounting screws, such as Loctite blue. Never use a permanent locking compound, because the heat required to remove the screws might damage the sight.
Holsters
Before choosing a firearm/RDS combination, you also need to look at the selection of holsters that will support your configuration.
Your existing holsters probably won’t fit your firearm with an RDS so you may need to buy a new one. Some holsters only work with specific RDS due to the size, shape and location of the sight, and many locking holsters won’t work unless your firearm also has a weapon light on it. It could turn out that a holster for your preferred combination either isn’t made or is back-ordered for an extended period.
Training
After selecting and configuring your firearm, RDS and holster, the next step must be learning to use it. Do not head out without appropriate training as you could be risking your life “fishing” for the dot when you draw your weapon while under fire. This article about the training program implemented by the San Mateo County Sheriff’s office might be a great starting point to understand what type of training you’ll need before hitting the street.
With proper training, RDS can breathe new life into older shooters and help new shooters come up to speed. But an RDS is not standalone. You need the appropriate weapon, RDS, mounting kit, mounting tools, holster and training.
This is a great opportunity for individuals or agencies to build a gift list for the upcoming holiday season. Have fun and stay safe.
