High capacity magazines have only one purpose.....They have no use in any sporting sport.
You do not seem to be familar with shooting sports. Maybe you should learn a bit about them, or even attend a shooting event to learn how much a standard or high capacity (7-20 rounds) magazine can benefit the contestant compared to something only holding 5-6 rounds.
Post this fact you have made up on http://www.thehighroad.org or another gun forum. I don't think there will any shortage of people there who will laugh at you.
Ranb