Here's an awesome sauce chart of everything you need from 3/16" to 1/2"
Man, that is awesome! Mucho thanks!
Where did you find that? Do you have access to the system or is that buried in a TM somewhere?
"MS" = Mil Spec
Simply Google the MS number.
I did-see
"I never have any luck googling NSN/#'s and getting anything other than govt. contractor sites."
Whenever I try to identify either MS or NSN #'s, all I can find are contractor sites that show they can order them and occassionally what they cost and that's it-there is never a description of the item.
I research car parts for a living-and I've done it for a while. I am not bad at it. In fact, I am pretty good. But I've had no luck finding a way to identify a lot of this stuff. If I am missing something obvious, show me and I'll take my ribbing.
For instance, the 1/2" one:
http://bit.ly/11saw6A
Of ALL the first page results, only wbparts.com and parttarget.com had any specs (and I must have missed them before, or I searched a different # that they didn't have).
There has to be some kind of central place to research this stuff.
Will these work?
Check McMaster-carr PN 95795A030. That get you to the right page to look at the sizes available. These are inside and outside tooth star washers with a minimum hardness of C40.
Other than those being zinc plated and me being after cadmium plated, they would work. I am being real picky about what I want, since it's going on this:

I don't have the info on 5/16, but I'm sure they can look up the p/n based on the below information.
Due to moving chicane's help, here are the remainder of the part #'s for those interested. All sizes represent inner diameter:
MS45904-60 3/16"
MS45904-69 1/4"
MS45904-72 5/16"
MS45904-73 5/16" ID with a larger OD
MS45904-77 3/8"
MS45904-80 7/16"
MS45904-84 1/2"
Much thanks to everyone for their help!
C