Critique someone's argument about gun control and provide a counterargument.
Arrogance and ignorance like that stupidly drives US gun politics. 
Your calculations are off and your modification of a 20-round magazine is a straw man argument. Bump firing a 50-round-magazine-equipped semi-automatic firearm takes about as long as it takes to change magazines (have a look on YouTube and educate yourself about bump-firing). Five-round magazines means five-round magazines. Modifying a large-capacity magazine blocked at five rounds does not apply.
I do know what I am talking about; I have owned long guns and shotguns, I was a hunter, a reloader, and I have fired handguns and fully-automatic weapons. I am not anti-gun; I am pro-sanity.
Why add Canada and Mexico? Canada is proof that gun laws work. Mexico? Really?
Blowing about how much you know about guns while talking nonsense is childish. Carry on.