I have experience enforcing and guiding this elsewhere. It was "safety." I'm only speaking rifles here. .22's could load up to 10 rounds but centerfire were limited ultimately to one round. It was a fairly ignorant rule which I changed permanently when empowered to do so. The thought was initially that fewer rounds were safer because the dangerous high-pwered round could be controlled more with fewer loaded.
It was a naive correlation, sorta like the one-gun-a-month or ten-round magazine laws -- an arbitrary lowered number makes one safer. To be fair, it DID make people count how many rounds they loaded and had fired so maximum limits did have some practical effect. And yahoos are everywhere. But it was also poor service to our average shooters and as this was an official, uniformed, function and difficult to explain to essentially anti-gun top leadership, change was slow and painful. We had our general orders.
I never did get more than ten-rounds allowed except when we permitted "testing" of magazines to their full capacity with "oversight."
This improvement, believe it or not, was an uphill battle and a good compromise as we allowed timed, slow and rapid fire but not what civilians would think of as spray-n-pray speed except in practical course and competitive shooting which operated at a whole other level, with marksmen, than the usual participant was involved in.
PS: we had benchrest types. We put distance between them and the typical shooter and gave them alot of latitude. Such known-to-us serious shooters often took one shot every 20 minutes, might clean their gun between rounds, and we even let them keep their hefty guns nestled on the benches pointed down range (bolts out, unloaded, cleaning rods down the bore) while folks went downrange to check and hang targets.
