ORIGINAL: majortom-RCU

Just for the record, all major brand metal servo hubs seem to use metric 3x.50 screws. Servo City has them in three lengths, the shortest being 8 mm. The stock screw on my JR metal hubs is 6 mm, but I tried an 8, and it fit OK. This size also fit my Hitec metal gear servos as well, a few chosen at random. The McMaster-Carr part no. is 91239A113 for M3x.50x8 button style socket heads, less than $6 for 100. The resin gear screws are metric 2.5x1.0 pitch, and that appears to be common for at least Hitec & Futaba; did not have a resin gear JR to check, but I bet they're the same.

Yes, mikenlapaz, McMaster-Carr is great for hardware shopping, best website I've seen anywhere for quick finding of what you're looking for, good prices, vast selection and fast delivery. They are my hardware store of first and last resort.