Mismatched Standards... Finding correct fasteners for mounting a 507c to S&W M2.0

[Tannhauser]

You were not “full retard”… it’s hard to wade through the different specs and then add aftermarket parts and screws to fit different footprints, threads, etc and it’s easy to find something that works until it doesn’t. We found the thing with the head diameter when 508Ts kept coming loose - we made the same mistakes.

PS - we now use the McMaster 18-8 stainless steel 6-32 x 1/2” screws for Holosuns (smaller head diameter) and they have been working great for us with degreased screws/threads/pocket and Loctite 248.

Can you share a part # for these screws?

[SoCalDep]

Can you share a part # for these screws?

The McMaster part number is 92703A255, but if you mounted with the factory Holosun screws and did it right (which based on your post I’m guessing you did) and there isn’t some defect somewhere in the system it’ll probably work just fine. I’ve used Holosun screws to mount a bunch of optics and haven’t had any issues.

The strength of the screw is down the list of important things when it comes to mounting correctly. If it’s mounted wrong it can come loose and even a strong screw will fail. If it’s mounted well and the system has an issue (ie: the screw head is too wide or the optic can shift too much in the pocket/plate) then it’s probably going to come loose no matter what and even a strong screw will fail. A decent screw mounted right in a good system will hold.

The biggest reason I like to use McMaster screws (which aren’t made by McMaster - they’re just a distributor and depending on what screw you order you’ll get different manufacturers) is that I can go and see where they’re made, what standards the fasteners (screws) meet, and a whole bunch of specs that simply aren’t provided in other factory or aftermarket screws.

[Tannhauser]

The McMaster part number is 92703A255, but if you mounted with the factory Holosun screws and did it right (which based on your post I’m guessing you did) and there isn’t some defect somewhere in the system it’ll probably work just fine. I’ve used Holosun screws to mount a bunch of optics and haven’t had any issues.

The strength of the screw is down the list of important things when it comes to mounting correctly. If it’s mounted wrong it can come loose and even a strong screw will fail. If it’s mounted well and the system has an issue (ie: the screw head is too wide or the optic can shift too much in the pocket/plate) then it’s probably going to come loose no matter what and even a strong screw will fail. A decent screw mounted right in a good system will hold.

The biggest reason I like to use McMaster screws (which aren’t made by McMaster - they’re just a distributor and depending on what screw you order you’ll get different manufacturers) is that I can go and see where they’re made, what standards the fasteners (screws) meet, and a whole bunch of specs that simply aren’t provided in other factory or aftermarket screws.

I’ve been following the procedure outlined here on Pistol forum for installing my Holosun RDS. I’m not going to pull them apart just to use a new fastener, but I foresee some swapping around of optics in the near future, and I think I will have some of these McMaster Carr fasteners to use for fresh installations I’m not really incredibly happy with the hollow sun fasteners partially because I need to strip off whatever that poor quality blue “thread locker” they apply.