Holosun 507C/Brownells RMR Glock Slide Issue

I finally received the Holosun 507C this AM after Fedex sent it on a 3 hour tour of the US.

Anyway, I am attempting to mount it on a Brownell's Glock slide cut for the RMR footprint. The trouble is, the 507 doesn't quite fit flush on the slide. It rides on top of the slide mounting studs. I can see daylight between the slide and the 507. The 507 rocks on the studs.

The mounting holes on the 507 appear to be bored uniformly. Why the studs aren't going all the way through the 507 is beyond me.

The Brownell's slide appears to be properly built.

I am genuinely puzzled.

Chatting with Brownell's tech support was a waste of time. He concluded I need a magnifying glass and precision measuring tools to complete the task.

A snug drill bit hand twisted through the 507 mounting holes indicated no obstructions or that the holes were tapered.

Still investigating.

Temporary(?) fix(?). I cut out a piece of copper tape (a leftover from an MRi install) to fit the optic cut in the slide. It measures 0.015" with the paper backing. No more red dot slop.

I think I'm battling the black oxide coating at the base of the threaded studs, which is not allowing the 507 to fully seat. Now, at 15 in-lbs, it's solid.

This is likely old news to readers here, but I experienced similar problems when attempting to mount a Holosun 407K optic on an OPTIC READY S&W Shield Plus pistol.

After some confusion and internet research, I discovered that when S&W made the OR Shield Plus pistols, they intentionally machined the mounting surface for the optic at an angle that slopes downwards towards the muzzle. Allegedly, this angle varies from 0.50 to 0.75 degrees, and as a result some optics may run out of elevation adjustment or be at max adjustment to obtain zero.

This issue was resolved by sending the slide to Nameless Armament, who re-machined the factory optic pocket flat, eliminating the factory angle. The rear locating lugs were also removed in the process and the front lugs were shaved down to a height of .025".

The process was fairly priced and completed in a timely manner, and the end result is a nicely fit optic that is secure and provides plenty of elevation adjustment if needed.

This is really odd to me. I just received and mounted a couple of 407Cs to a couple of Brownells slides a few days ago with no issue. I’ve had numerous Brownells slides with the Holosun combo and it’s always worked really well for me. This combo is my go-to budget setup for an RMR cut slide. If it were me, I’d send that slide back and have them send me another just in case the slide is out of spec. I will say that the fit is rather tight by design, but still, obviously not having it in front of me, I’d assume there is a problem with that particular slide.

Quote:

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Originally Posted by NETim

I finally received the Holosun 507C this AM after Fedex sent it on a 3 hour tour of the US.

Anyway, I am attempting to mount it on a Brownell's Glock slide cut for the RMR footprint. The trouble is, the 507 doesn't quite fit flush on the slide. It rides on top of the slide mounting studs. I can see daylight between the slide and the 507. The 507 rocks on the studs.

The mounting holes on the 507 appear to be bored uniformly. Why the studs aren't going all the way through the 507 is beyond me.

The Brownell's slide appears to be properly built.

I am genuinely puzzled.

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Quick update - I just had a similar issue with my Brownells slide and a Holosun 407. It was a super tight fit getting the dot on, and even though I was able to mount it after tapping it on with a rubber hammer, there is a slight gap in the rear that is visible when pointed up to a light source. There is also some rubbing on the rear of the optic body, telling me that the Brownells optic cut is a tad out of spec. Out of the 10 Brownells slides I’ve had, this is the first one with any sort of issue.

Im going to keep it since I got it on sale and with a discount code for like $80. I’ll see if it’ll still hold zero. If not, I’ll put a cover plate on it and run it as an irons sight setup.

I would sent it back.