I guess it is sadly a legitimate concern.
Probably the most practical gun for dealing with large number of wild acting criminals would be one of the Glock or similar guns which now come with really hi capacity mags and are immediately ready for shooting as soon as the gun is in your hand.
Since I can’t afford a new one right now, I would probably wear my old Browning Hi-Power. Although it protrudes a bit, I would have one of the Mec-Gar 20 round mags in it.
Cocked and locked it would be nearly as quick despite having a small safety lever. That would be 21 shots fast in a gun which is easy to hit with.
The time it takes for target acquisition and sight picture is significantly longer, and more important, than attempting to hose down a perp with lead and killing innocent bystanders.
Take a two day class to learn how to run the gun, and commit safety rule #4 to memory.
The Hi-Power far more concealable than one might expect. I have one, and carry it in cool weather.
I recommend against carrying it with the 20rd mag in it. It really does stick out too much. Standard mag is 13 rds (you already know this), and flush-fit 15rd mags are available. Ram-Line makes (used to make?) them, among others.
If you want have the extended mags, carry them as spares. It'll be a lot more comfortable that way, and you're more likely to actually carry the thing.