Only people emptying a hi cap magazine are mass shooters and criminals. As mentioned before mass shooters have been stopped at reload, why do you want them to fire more before reloading?
Well, criminals and mass shooters will get standard capacity magazines if they want them...they will get them illegally, just like they can get guns when they want them...
If someone isn't a criminal...who cares how many bullets they have in their pistol...since they aren't going to abuse them in the first place? And are you psychic...do you know how many bullets someone will need....
There was a woman with two children who had a man break into her house...she fired 6 rounds...the first missed the next 5 hit and he was still ambulatory...luckily for her he had had enough and fled the scene...what if he had had one or more partners...6 shots would not have been enough...what if they had guns and a sustained gun fight took place...more than 6 rounds may be needed...what if she was wounded in the initial fighting...should she have to try to reload, wounded, when her small motor functions are compromised and she may mess up the reload simply because you put an arbitrary limit on how many bullets she should have in her gun....all because criminals might put a lot of bullets in their gun....which they will do any way...because they are criminals and will get standard capacity magazines if they want them?
What about an isolated rancher in Texas or Arizona...who might encounter members of drug cartels crossing their land...you know...the guys obama sold actual military rifles to...and he has to hold out for 30 minutes to an hour or longer before any help is even close to helping him...do you think he might want more than 5 rounds in his rifle or pistol?
Who are you or anyone else to say how many rounds a legal, law abiding citizen can have in their constitutionally protected weapon?