To say we train with a small number is weapons is unfair, I'm proficient with and qualified to instruct: C7 (5.56 rifle), C8 (5.56 carbine), C9 (5.56 light machine gun), C6 (7.62 machine gun), 50cal machine gun, pump action shot gun, 9mm pistol, m203 40mm grenade launcher, 60mm mortar, 84mm rocket launcher.
On the caliber issue, perhaps there are few different calibers for the rifles/mg's, but the soldiers have a solid understanding of how different weapons work. For example, the C7 and C9 both shoot 5.56, but the C7 is DI and the C9 is piston based.
As am I, but of all of those things only 3 of them are available in the civilian world: the shotgun, the semi-auto pistol, and the semi-auto rifle (C7 and C8 being the same thing). A basic understanding doesn't mean anything when you have to use a single action revolver. I know several people who have gotten a PAL after several years in the military, and were surprised at how little they knew. Just changing some things on the course for a "conversion" now makes another standard, and wastes time and money. The army teaches you to "put issued bullet only in issued rifle". You can't get it wrong. In the civilian shooting world there are lots of different things that can go wrong. I also disagree that soldiers have a "good understanding" of how their weapons function. We teach weapons DRILLS, not "understandings". I'm not trying to be rude, but I am continually surprised at how many soldiers know so little about their weapons systems. This is the "put up your hand and ask for range staff" syndrome.
And I will add that MOST of the CF is not qualified or experienced on all of those weapons systems, and have only done basic training and a once or twice a year practice with their service rifle or pistol. I think it's a good thing that the government says "hey, before you can buy ANY firearm you want- you need to know how to handle most of them- to a reasonable standard".