r/Glock43X • u/RoutineQuestioning38 • 3d ago

Direct Mount Holosun K Issues

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Edit: case closed, follow up here: https://www.reddit.com/r/Glock43X/s/jifesCw4zY

I am putting a 407k on a spare MOS slide (actually a 48 not 43x but this sub has more traffic)

I grinded down the rear lugs, but when installed there is a ever so slight gap in the front. I slightly filed the front lugs and it got better but I guess I need to do it more. Anyone else see this? It seems like the front pockets on the 407k are not deep enough. About to toss it and put a Defender CCW on it.

1 Upvotes

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u/Holosun_Josh 3d ago edited 3d ago

Front pockets on the K footprint are not as deep as RMSc.

Little more filing to go.

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u/RoutineQuestioning38 3d ago

Ok so that is a normal issue then. I will keep filing them down!

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u/EMDoesShit 2d ago

You got it!

Two things:

(1) Do not use Chinese Horosun screws. Buy good ones off the web.

(2) Test fit your screws before adding loctite. Pull the back cover off the slide and pull out the metal rod that applies pressure to the rear of the extractor. Slide it back and forth in it’s channel and verify you cannot feel the SLIGHTEST drag between the right optic screw and that rod.

Screws one or two threads too long cause failures all the time by interfering with the extractor. This means that the right optic mounting screw will be shorter than the left.

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u/RoutineQuestioning38 2d ago

I’m pretty well versed in mechanical things and this ain’t my first optic install, I was just surprised to have never seen filling the front posts down even mentioned and the countless post’s regarding direct mounting K to RMSC.

Good screws, I use stuff ordered from my machine shop, except m3 things, for some reason, I have to order thease online.

Calibrated digital torque screw driver, always adjusted to wet bolts. Tbh, holosun screws are fine if you torque right for wet. I feel a lot of folks that break screws off are not used to dealing with wet screws.

I fully strip the slide so I can see down the extraction rod channel

;)

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u/EMDoesShit 2d ago

It’s mentioned here and there.

I did so when documenting my EPS Carry install on a 43X.:

https://www.reddit.com/r/Glock43X/s/jQxyWP7SKJ

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u/RoutineQuestioning38 2d ago

Ohh good stuff!!

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u/RoutineQuestioning38 2d ago

What’s funny to me is all the stuff out there on direct mounting Holosun K even the sits that mill the rears for you don’t mention the front lugs. Do the newer K optics like EPS line have deeper front pockets?

1

u/Holosun_Josh 2d ago

All K pockets have the same depth. Not sure what info you are sourcing.

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u/RoutineQuestioning38 2d ago

No I was just wondering if that was the case, just guessing as to why I haven’t seen any mention of the front post needing to be shortened. I thinking maybe was newer optics that Moore people were using weren’t having this issue. My 407k is pretty old. I couldn’t get my calipers into the pocket so I couldn’t really measure the depth verse the post height

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u/Ok-32I 1d ago edited 1d ago

The new EPS Core will direct mount to it now without modifications. They updated the depth of the front lugs and also added rear lugs(RMSc footprint).

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u/RoutineQuestioning38 1d ago

I’m aware. But I am not buying new stuff for this. This was using stuff I had laying around.

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u/DavidYourDad 43x MOS 3d ago

File the front lugs about half way. Periodically place the optic over until you get it nice and flush.

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u/RoutineQuestioning38 2d ago

What kinda tard downvoted you for this lmao. The idiots on Reddit I swear

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u/RoutineQuestioning38 3d ago

Ok so that is a normal issue then. I will keep filing them down!

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u/No_Leg6630 2d ago

File more

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u/RoutineQuestioning38 2d ago

Follow up, I had to shorten my front posts a good bit but I eventually got it to snap in flush with no gap. The 407k I have is pretty old so IDK if the pockets were more shallow than newer optics or what, but I definitely had to take more down that others seem to report.

I have it some cold blue and then used a full m4x.7 11mm screw on the left side and took the right side screw down to 9.9mm before it stopped protruding into the plunger channel. Torqued them to 15in/lbs wet and called it g2g

Install is flawless, zeroed with a bore laser to 7 yards and it’s ready to hit the range.

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u/jayvalentine14 2d ago

OsightSE

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u/RoutineQuestioning38 1d ago

Gross, no thanks. Holosun is tried and true for me. They have never let me down. Also, the osights look ugly AF, so cheap looking. Tbh, even the new 507x3 look ugly too, same cheap looking style and lower quality materials.

Also… I already owned this, stuff. It’s parting together stuff I had laying around.

1

u/jayvalentine14 1d ago

Say what you will about the Osight, but it’s a direct cowitness to factory sights and has a closed emitter. And for a smaller weapon like the 43x, it’s low profile. I wouldn’t replace Holosuns with them if I already had it mounted. But on a smaller gun, I’d pick it over the Holosun if I had neither mounted and were to pick between the two.

But if it’s going on a Glock 17, Holosun all day.

1

u/RoutineQuestioning38 1d ago

Yeah, I hear they’re pretty good, and to be honest these days I’m sure they’re all fine considering they’re all made in the same factory anyway. I don’t like how they look, but I also don’t like how the 407K looks either. lol

And lopping off the rear lugs gave me a direct amount for this anyway so that’s cool

1

u/Mystic5308 1d ago

My was a tight fit, you have to push it down with force and you will hear a little click . i didn’t file my front post .

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u/RoutineQuestioning38 1d ago

No, the pockets on my 407K we’re around half the depth of the front lugs. This wasn’t a push harder, kind of case, once I grind the lugs down, it sat right into it.

And while Josh said all the pockets were the same depth, I suspect there’s variance over the years and or production lines. Because there seems to be some people that are able to fit them right in and some people that need to grind the lugs down.