Saltfever;
I like to use MIL & aerospace surplus hardware when I can. The MIL/aero stuff that I've accumulated over the years was made before counterfeiting became a widespread problem. Also, those fasteners are comprehensively specified with size tolerances and strength specs. I'm very leery of "Grade 8" fasteners but I use them when I must. It's just that you are depending on too many unknowns with "SAE" stuff. Bolts made by SPS, Allen, Carr, etc are only "industrial" grade stuff but I've found them to be excellent quality to date. A few years ago I bought a packet of ARP hex nuts and found one nut that was missing the threads-- just a smooth round hole. Not inspiring quality.
Regards, Neil Tucson, AZ