Where are you and "how" sub do you need? I was just at the WalMart in Marlin (Falls County) and they had a lot of standard velocity CCI .22LR with a MV of 1,070 FPS on the box. That's just barely sub-sonic and might be closer than you want. Just throwin' it out there. Good luck with the new can, sounds like fun!
"I have no idea what WW-III will be fought with, but WW-IV will be fought with sticks and stones."