Posted: 5/9/2026 10:15:14 PM EDT
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I just got an optic ready S&W Shield Plus. Apparently Smith uses #6-32 mounting holes (a 5/64” hex key fits the screws, which matches that size), but my red dot came with both M4 and M3 screws of different lengths. So I need two countersunk #6-32 cap head screws. I haven’t measured the length I’ll need but that’s a minor detail at this point (it’s probably 1/2”). I don’t want to trust Amazon’s sources for precision screws without some vetting, but I’d prefer another reasonable source if there is one. Unfortunately, I don’t have a big wish list with McMaster-Carr, and buying 1000 of these screws isn’t practical  , so that’s not a good option for me. I’d appreciate any help folks can provide on this. Thanks in advance. |
When you have to shoot, shoot. Don't talk.
Joined:
Jun 2003
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PA, USA
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Originally Posted By Piratepast40: Do a quick internet search. Amazon has several kits with various sizes. That’s what I did. I’ve had mixed luck with Amazon’s “scientific” stuff like small fasteners, but adding “RMR” to the search gave me a bunch of good hits - and I didn’t see any that looked like they were from “Lin’s Melamine Milk Company”. I ordered one set that has more than I’ll need, and I won’t have to even measure, just try this length versus that length. The sight is a Swampfox Sentinel, the original version. It came with two lengths of 4mm and one length of 3mm screws, aimed at SIG and other brand’s mounts. Since it was pretty inexpensive, I’m not upset at having to buy a different set of fasteners. I do have some issue with S&W not bothering to say what size their mount hardware is…I spent quite a lot of time searching online to find this out. |
| Be aware that if your optic came with metric screws, it likely has a 90 deg countersink. If you get SAE screws, they’ll have 82 deg. Companies like Holosun typically include a set of SAE screws with 90 deg taper or you can call them and ask for some. |
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The screws came in. The #6-32s (there were also #6-40 and #6-48 in the pack) have a shank that is a close fit to the optic's mounting holes, and a button head that is very low. They don't interfere with anything, and they're quite secure. The 12mm long screws fit perfectly, but I had to chase the slide holes with a plain screw because the finish seems to have built up in them. Since the screws came with blue threadlocker on them, I didn't have to use my own. I cleaned out the holes with degreaser and alcohol before installing to make sure the threadlocker worked. The instructions for the optic, a Swampfox Sentinel, say first that the gun maker should provide screws, and that you should use the gun maker's torque specs. Nope for both from S&W, but the instructions say not to go over 15 in/lb, so I torques them to 10 in/lb. I've boresight-zeroed the sight, and when I can get to the range I'll tweak that. I'm really happy with this setup and I'm looking forward to getting used to using the dot instead of irons. |
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I grabbed a pair from Battle Worx for getting my RMR mounted to my G17.6. Particularly because they were a T-15 instead of the standard T-10 that everyone includes and that seemed less likely to strip than the smaller ones. Make sure they match optic and slide though. Different optics have different counter sunk bevel angles. |
