At the end of the day, everyone will tell you to experiment and that each kit seems to like differnet ammo.
That said, my $0.02 is that it is more fun to shoot than experiment so do yourself a favor and start your experimenting with the ammo that Vector uses, Winchester Super X High-Velocity. (It also happens to run flawlessly for me)
A common problem people experience with the 22 kit is that the ejector in your receiver is too long and extends over the 22 round sitting in the top of the magazine. Either you (or Vector) can file the ejector back a little so the 22 rounds clear the ejector. I had Vector do mine because I didn't want to screw it up but some people here are more competent than I am. The original directions that Vector included with its 22 kits speaks to this issue and how to remedy it. Good luck and happy shooting!