Originally Posted by Wash-ar15
I think 18 rds per stage is the max
Correct, Sort of.
Eighteen (18) is the maximum REQUIRED round count - unless limited you are free to shoot up to division capacity - for SSP that's thirty-one (31).
In any semi-auto division you are only allowed one (1) magazine in the firearm and two (2) on the belt. An extra "barney" magazine is allowed on the belt (as I recall?) or pocket. A "Barney" is used to chamber a round upon "load and make ready" and is empty before the CoF is started.