I can't help with a direct answer to your question but when I needed spare grub screws for one of my RTA's I simply measured the dimensions with a ruler and searched on ebay. Successfully.
I got a bag of 10 from Kays Fasteners (kayfast1) on ebay for a couple of quid. The first ones I ordered were too small, my mistake, and they were super helpful and sent me the ones I should have ordered with no fuss.
I've looked at the V4 spare screws I have in the box and measured them, as best I could, and I think they may be M1.6 x 4mm (or maybe M2) Pan Head Pozi Screws. Please don't accept my measurements -Best measure yourself to be sure as my eyesight isn't 20/20!
Check the measurements, have a look at the link above and good luck.