Maybe the "magazine gauges" are in short supply and the rookies have to use the old fashioned method of checking for a plug. 
Actually, I think the issue is the multiple shotgun shell lengths. Now that there are 3 1/2" chambers, the officers want to know if you can load three of
your cartridges into the magazine. It's not as simple as it used to be. If you can load three of your 2 3/4" shells, you're busted, even if the magazine will only allow two 3 1/2".
