Yup, its now some sort of rule that all reservists have to be issued with anti-gas respirators because they don't like giving them out on the BSSC.
I expect the regulars would probably be able to correct me here if I'm wrong, but I believe that normally the regulars get ALL their kit and gear issued during their basic training at HMS Raleigh. So when reserves go to do their BSSC the stores personnel are often unhappy about giving away their precious respirators. How did that famous line go? "Stores are for storing, not for issuing".
I've been told that its now impossible to get on a BSSC without an AGR, and if anybody does somehow manage to appear without one, they'll simply be returned to unit.