So I splurged on a Unity AXON light/IR laser remote switch, and as I was attaching it to my rifle with the mickey mouse mounting system, promptly dropped a nut and could not for the life of me find it.
So off to search in the teeny tiny bolt section of the hardware store. Using the store's gauge, it's a #5 size. The little hardware store in town actually has an impressive selection of bolts/nuts in all sizes/types. Except #5. They have 0,1,2,3,4,6... but no #5. So I also did a quick Amazon, and maybe my Amazon-fu is weak, but they also seem to sell everything but a #5. Same with Home Depot (who doesn't even have small sizes. So I'm just curious if this is some oddball size. The hardware store did have #5 sheet metal and other screws, but of course I needed a nut.
Which, even if I find one, it might not do me any good. For kicks I was trying a #4 nut, but also held it up next to my remaining #5 nut from the mounting kit, and the Unity #5 nut has a WAY smaller outside dimension than a (I'm assuming) standard #4 nut. The nut has to sit in a recessed opening in the mount, which leads me to believe they are using some kind of oddball size. It almost reminds me of hardware you would see on a motherboard or something. I have an email into Unity to verify size, and apparently other people have had Unity send them replacement hardware for free, but of course they haven't gotten back to me yet because they're emulating HK with the customer service.