There absolutely is a reason for a 30 round magazine such as a Glock or an AR-15 has.
The reason is to match the 30 round magazine that an M-4 has.
Never miss the point. The second amendment was written for one purpose. It was written so that the people of this nation would possess the ability to fight if necessary. That implies killing.
I would hope that prevailing in a conflict was implied and that symbolic gestures of resistance were not the full scope of their intent.
Colt M1911, AR-15 | S&W Model 19, Model 27| SIG P238 | Berreta 85B Cheetah | Ruger Blackhawk .357MAG, Bearcat "Shopkeeper" .22LR| Remington Marine Magnum SP 12GA., Model 700 SPS .223