I am a newbie to these guns, just purchased the R9S SF 2 on Apr 14, 09. I was interested to know about bird shot in this gun and stumbled upon this conversation. As of the last posting, no one seems to have fired rat shot (or bird shot) through their R9.
I just fired a few rounds through mine. Everything cycled perfectly and performed as expected.
I agree about sitting on the tractor and trying to hit a snake... Bird Shot will make this a much easier task.
Ammo: CCI Shotshell Ammunition 9mm Luger 64 Grain #11 Shot Box of 10
http://www.midwayusa.com/viewProduct/?productNumber=709816