The L98 fires the 5.56 round, there is just no selector for Full Auto The other common rifle that the air cadets use is a modified Lee Enfield which fires a .22 round. Some people get lucky though and end up firing other stuff such as the L86. Definitely listen to the range officers, someone in my team managed to load two rounds 1 behind other in the breach once...
He managed to brake of the tip of something in process, cant remember what it was but it prevented the round going off into the second one. He also had a long discussion with the Wing shooting officer afterwards...