#MadeinchinaOriginally Posted by MandoWookie
I took the screws to both Lowes and Home Depot and both stores close to my home had the appropriate sizes. I think 5mm for the M&P hex heads and T-15 torx for the factory Holosun screws. I, too, noticed they specified a torque value and then provided a simple Allen key 🤪
The problem isn't with the optic... Holosun can't predict what platform you're going to mount it on. It has an RMR footprint, which means traditionally that you'll likely mount it with 6-32 screws, but again - that depends on the threads in the slide. I'd be more frustrated that the slide didn't come with screws for the two common RMR footprint optics (RMR and Holosun) which would have made mounting simple and easy. Since it didn't, you get to figure out what to do.
The Holosun, while an RMR footprint, uses a smaller screw head diameter, so finding screws that work and are of proper length can be difficult. Since I don't have the dimensions of the screw holes in the specific slide you have, I can't give specific screw dimensions to use. Screws for the Glock factory MOS system for the RMR are 6-32 x 3/8" and for the Holosun are 6-32 x 5/16". This is a good place to start. I use Zinc-coated steel screws from McMaster-Carr for the MOS/Holosun screws since they are the only 5/16" screws I can find at a reasonable price in that length with the correct head diameter.
Worst case, use the longer screws if the left one will seat, and with the right one, disassemble the slide to allow you to see the extractor assembly channel, see how much the screw protrudes and get busy with the dremel, a file, or a grinder and shorten the screw until it no longer protrudes into the extractor channel. I've had to do that with a Glock 48 and C&H screws that were the wrong length.
One thing to remember is that the drive size (ie: T-10, T-15, or whatever hex size in Metric or Imperial) is somewhat independent of the required dimensions to fit the interacting parts. I have screws that are the same length but have different size heads and use different drive sizes. One should only be concerned with drive size for the purposes of using the correct wrench or bit. As far as fitting the optic the overall dimensions are what's important. The alloy steel screws I use for the RMR have an IP-15 (T-15 bits will work) drive, while the zinc plated steel screws I use for Holosuns on a Glock MOS have a traditional T-10 drive. The factory S&W CORE screws (cover plate and several of the included screw sets) are 5/64". The factory Holosun screws are T-10.
Once you get the screw situation figured out, prep everything (screws, slide pocket and threads) with degreaser - and alcohol works well. I use 71%-ish alcohol pads and get into the threaded holes with a toothpick and it works well. I test fit the components to make sure the screws and plate (if applicable) fit with the optic and slide. Apply threadlocker to screws - I like Loctite-248 but 243 is good too and a bit stronger (but messier as well). Tighten to the appropriate torque. Optics have a spec. Aftermarket plates have a spec. Slides have a spec. Only tighten to the lowest spec of any interacting component (I will deviate from this based on experience with specific components but don't recommend it in general). RMR-footprint Holosuns such as the 407/507/508 series have a torque spec of 15 in/lbs - the question is; what is the slide's torque spec? I doubt you'll get it so that 15 in/lb will probably work. Once you've alternatingly tightened each screw to the spec, make some indicator marks with a sharpie or oil-based paint pen (I put the paint on the alcohol-pad's wrapper and then use a toothpick to apply) to hopefully catch if the screw/screws come loose. If they do, don't re-use them. Use new screws (which means trimming the length again if applicable).
Whelp, still working this with Holosun. They did end up sending me a tracking no. on 3/28 after I followed up with another email. I was out of town till today, and opened the package they sent. Unfortunately, there must have been some kind of miscommunication, because all I got in the envelope was six sets of four (two and two) mounting screws of some kind. They aren't battery tray screws, since they are T10 Torx and way to big to fit. I re-emailed Holsosun again for a third time. I'm about ready to order a few replacements from Battlewerx, but dang, $5.99 apiece is kinda spendy. Alternatively, does anyone know the dimensions / thread pitch for a battery tray screw for a Holosun 407k?
Okay Agency screws came in, did a dry mounting just using the included tool, everything fit good.
Plan is to work on it this weekend, degrease slide with alchohol, use loctite and E6000 like JCN recommended in his thread, mount up.
Do live fire and sight in Easter weekend.
Holosun ACSS Green reticle I noticed is blurry when I'm looking through it indoors, but outdoors it is sharp. Auto adjust seems to work fine with a slight delay.
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Got a second package today from Holosun with a new battery tray and two screws.
Much appreciate their helping me out on this, as it was my fault I let the screw get lost in the first place.
I have several Holosun red dots, but the just-received 407CO is behaving strangely. The buttons are definitely an invention of the devil size-wise with close cropped fingernails. That aside I've cycled through the three modes (auto, manual, lockout) several times and I can't find a "manual" mode. I do get the single blink after holding the "+" for 3 seconds to I'm clearly cycling through the modes. Just wondering if anyone else has experienced this sort of think with a new out-of-the-box optic?
The typical approach I use is to first replace the battery while I think what else to do. Duracells have been mentioned up thread, I've switched to those and have had 0 problems. I mean, yes it's a new optic but the battery might be sketchy, and it's an easy thing to do as a first step?
Yes, I had this happen on a 509t. Luckily I bought it locally and was able to go back, where we changed the battery and it still didn’t work correctly. Then they exchanged it for a different one that did work correctly.
Changed the battery and now the 407CO is stuck in manual mode; no mode change blink after 3 seconds of "-". So, back it goes.
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