This is a newb question...I just bought a steer lp2 to shoot with a local club, I don't yet have a hand pump and so a friend at the club has charged my pistol for me so i can train a bit in the basement is there a time limit of how long it is ok to keep a canister charged?
There might be, but if you reach it then you probably didn't need the gun anyway ;-)
I have the same cylinders on my LP5, which I only shoot once or twice a year. The cylinders are charged as soon as I get home from the match, and there they stay for the next 6 months (or more).