I'm going to toss out some of the counter arguments to switching to air rifles. The CNo.7s are big, long, heavy and old. They haven't been made since the 1940s, and all stocks of parts have been thoroughly triaged trying to make do. For Wpns Techs who expect to see neat and tidy parts drawers, they are a challenge. Soldiers are not taught to 'fix' things, but make them serviceable. And that is just about impossible when every third rifle needs parts. (No slight against the Gun Plumbers, but not every one likes or cares about old guns.)
The air rifles are easier to shoot. They don't put lead dust into the atmosphere. And for anyone who has to cajole or mollycoddle school or CF range administrators or CF medical boards, that is like army wrestling with an octapus.
The air rifles are lighter, easier to #### and don't need to be locked up to the same security orders' standards as firearms. If you want to get depressed, read the Security Manual for the CF. So many things to do and get charged with if not done.