Oh cheetos, yeah you’re right and thanks for the welcome bro
1 Like
My Rock is still on its way to my FFL, but I do have my Holosun HS407k X2. When I place the Holosun screws into the sight they protrude 5.4mm below the base. If the slide can only accept 3.8mm (I plan to check this on my slide) I guess I’ll shorten the Holosun screws by 1.6mm. The screws come with thread locker on them. After shortening I may have to add more. The adventure begins.
2 Likes
Welcome to the forums @dmurawski 
I have the optic ready 57. I want to install a Holosun EPS G MRS on it and would appreciate some guidance. I believe this is called the K footprint and mounts directly to the Rock without using any adapter plate . The Holosun comes with two sets of screws a short set and a longer set. If I use the longer set it on it I can only get about a quarter turn of the screw into the Rock. If I use the longer screws that came with the Rock I was concerned about damaging it based on what I have read on this thread. (The smaller screws don’t reach the Rock’s slide). Thank you for your input and assistance.
1 Like
It’s a little work, but you can take the striker housing out of the slide. Then it will look like the pic above. Mount your optic and see how far your screws expend beyond the slide. Shorten them until don’t extend beyond the slide. Reassemble, function check and have a celebratory beer.
4 Likes
I would put the slide under a towel or in a t-shirt bag to remove that rear cover plate and putting it back in. The rear cover plunger and striker spring are capable of space flight on disassembly/re-assembly.
6 Likes
I measured the depth of the Rock MRD mounting holes from the top of the slide cutout to the top of the striker assembly at 3.84mm. Measure the thickness of your MRD base from the top of the mounting holes to the bottom of the base and add 3.8mm. That is the maximum length screw that will not penetrate the striker housing when fully tightened. Either shorten a longer screw to just below the maximum length or use a standard length screw that will give you enough thread engagement to guarantee the screws will not move under recoil.
1 Like
But if the screws you will be using are countersunk into the optic’s base, I’d suggest you insert the screws and measure how far they extend past the base. Shorten them to not exceed more than 3.8mm and use BLUE Loctite.
I took my new 5.7 out to the range and it worked great with various ammo.
Now mounting the optic (507Kx2). Took the striker assembly out and saw it had similar damage as Fogus has in his pictures, but not as sever.
Do they mount an optic at the factory for function check?
Welcome to the PSA community @Buffalo309 
1 Like
This information was exactly what I needed. The only screws that came in the carrier was for the cover plate. Really appreciate the information provided:
A: That doesn’t look like the screws that came with my Holosun.
B: I have one with remarkably similar cosmetics with the striker housing. Filed the screws down, pushed the deformed pieces back up and it’s been running fine. I may or may not have 3 of them and they all run fine.
I have four 507Ks and they all came with a pair of 12mm long M4 small flat head T10 Torx screws with a shiny black finish that fit flush in the Holosun Mounting holes. They also came with a set of similar 6-48 screws for use with other firearms threaded for that thread size.
Those are the M4 10mm which were suggested earlier.
Not pretty but were a perfect fit for the inside of the slide.
The two screw sets which came with the optic didn’t work.
The only set I received with the gun were for the cover plate.
Indeed. Have a drop down ceiling and thought the plunger was going to go through the ceiling tile. Glad is a good size so was able to find it.
If you want to make it pretty, take the pair of m4 x12mm screws that came with the 507 and shorten them to 10mm. It’s simple to screw them into one of the adapter plates that came with the Rock mounted in a vice and slowly file them down until they protrude below the bottom of the Holosun base when inserted the same distance as the ones you have installed. You can’t just make them the same overall length as the heads on yours do not fit flush with the base so the thread doesn’t protrude below the bottom of the base when installed as far as the Holosun provided screws
1 Like
I used a wire stripper with a built-in screw cutter built-in. Worked great.
1 Like
I also used a wire stripper screw cutter but it was a little pricy at $20 to get one that fits M4 screws on Amazon. For those who don’t want to spend the extra $ or wait for shipping, using the mounting plate and a file works just as well if a little slower ( I’ve done that as well ).
1 Like