Unsuccessfully Installing a RMR on an Optics Ready VP9

Just when you think you have everything you need to assemble an upgrade or a customization is exactly when things don't go as planned.

It’s no secret, I’ve really enjoyed shooting the H&K VP9 over the past couple of months. Take that excitement coupled with an addiction for new gear, old eyeballs, a bit of jealousy when one sees all the cool kids using carry optics on their pistols, and one might just end up deciding to try their hand with carry optics. Which is exactly what I’ve started to do. However, it’s been a bumpy road.

I started feeling the itch back in mid January. At the time, I had already settled on starting out with a Trijicon RMR as the red dot sight I wanted to start with. In my eyes, it’s the measuring stick that all other carry optics are measured by. So it felt like a natural place to start.

At the same time, I thought the best option to add the RMR to the VP9 was to have the slide milled by a gunsmith. A bit of internet google fu led me to find a couple of gunsmiths who were willing to do the work and several others who wouldn’t touch the project for various reasons.

The three gunsmiths I was considering were:

  1. L&M Precision Gun Works
  2. Ashbury Precision Ordnance
  3. Parker Mountain Machine

Hearing several gunsmiths refuse the project gave me pause, but at the time milling the slide was the only option unless I wanted to replace the rear sight with a mounting plate from the HKParts.net. Those were the options.

While I was contemplating my choice between sending the gun in to a smith and going without for several weeks or purchasing a second slide for the VP9 and sending that in, I came across a blog post covering H&K’s announcement of an optics ready edition of the VP9 at Shot Show.

This option was the most attractive to me. This option allowed me to retain the front and rear sights which I could replace with suppressor height sights to use as back up sights or as a co-witness. At the same time, this option allowed me to keep the manufacturers warranty intact. So this was the route I went.

After placing an order for a new VP9 with GrabAGun.com, I went over to Amazon and placed an order for a Trijicon RMR. Then I went over to the H&K Web Shop and placed an order for a #2 optics plate (compatible with the RMR). Several dollars later it was just a matter of waiting for some of those items to arrive and for a call from my local FFL to pick up the firearm after completing the required background check.

That brings us to today. Also known as assembly day.

Let’s walk through the assembly…

Remove the Cover Plate

Easy enough. Just remove the two screws exposed on the top of the slide and remove the cover plate.

Didn’t even need to crack open the manual.

Assemble the Adapter Plate and the Red Dot Sight

Seems easy enough. One just needs to screw the adapter plate to the slide using the screws that were removed when the cover plate was removed. Then screw the red dot sight to the adapter plate with the screws provided with the red dot sight. Easy enough. Right?


The Devil is in the Details

Let’s start with the first little detail. How much torque should be applied to screws that will be used to secure the adapter plate to the slide? I figured this was in the manual. However, all I could find in the manual was that a torque wrench capable of applying 2-10 Nm of torque was required while step five specifically instructs to “tighten screws until the torque is reached”.

No problem. I’ll just call H&K. Which is what I did only to be informed that all they can provide is the same information I found in the instruction manual since that’s all the information they get form Germany. This is pretty surprising to me because the difference between 2 Nm and 10 Nm of torque on a small screw is pretty significant. Significant enough to snap heads off screws and strip screwdriver bits. The customer service rep at H&K was kind enough to patch me through to one of the repair guys hoping they may have some more specific specifications, but that ended with me leaving a voicemail and moving on.

I torqued down the screws on the adapter plate to 18 in-lbs (just north of 2 Nm) without using any Loctite (as per H&K’s suggestion) for the time being.

Of course, this dummy missed the specification engraved directly on the adapter plate.

Moving on to attaching the RMR to the plat, which also had a similar missing detail. How much torque should be applied to the screws that attach the RMR to the adapter plate?

This information was missing from the RMR’s manual, which led me to call Trijicon. The customer service representative was quick to respond with 12 in-lbs. This sounded about right to me given other torque specifications for similar sized screws I’ve come across.

The rep at Trijicon then asked me about what I was mounting the RMR on to and proceeded to walk me through a few things. Here is what I found.

  1. The sealing grommet on the bottom of the RMR is slightly visible from the side edges of the adapter plate that meets the RMR. This makes me wonder about the quality of the seal between the RMR and plate. To address this, Trijicon suggested I pick up and install a RMR mount sealing plate (I’ve placed an order for one).
  2. After torquing down the screws between the RMR and adapter plate I notice quite a bit of play and wiggle between the RMR and the adapter plate. I called H&K back with regards to this and was told that they mounted several RMRs to VP9s using the provided screws for Shot Show and didn’t have the problem I reported.

I did take a moment to remove the adapter plate from the slide and attach the RMR directly on the plate to see how far the screws protruded out of the bottom of the plate and found some interesting information.

First is that the screws do protrude a bit as seen in the picture below. It also looks like the right side protrudes a bit more than the left side. I estimate the protrusion to be at least 1/8″ but I’d have to get my micrometer out to be certain.

While there is a little clearance on the slide itself for a protrusion, I don’t think it’s enough clearance for the screw on the right hand side. This is more evident when I gently place the adapter with the RMR secured directly on the slide.

Next Steps

Time to get back on the horn with H&K and Trijicon. I can’t imagine that I’m the first customer who has had problems with mounting an RMR on a VP9. Now I may be the least informed customer or the densest, but I’m sure I’ll get this figured out. When I do, I’ll follow up with another post.


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