What's the maximum clip capacity on those?
Using a Barreta as an example. The clip will hold 15. With one round in the chamber the firearm will have 16 shots.
Depends on the make/model.
If I had to guess on a gun type, I would say a Glock since its widely popular, so somewhere between 10-15 rounds per clip. For 50 people he probably needed between 4-6 clips or more.
Heard on Fox that some clips may hold 17 rounds. This guy must have been very well trained to get off that many rounds, reload quickly, and not get jumped. Plus he lock the doors with chains. He was prepared.
I have after market 17 round mags for my Ruger.
I have a 9mm Ruger and I have some clips that hold 40 rounds. I can change clips in about 2 seconds.
Among commonly available sizes, and depending on the handgun, up to 30 round *magazines* are available.
The last “clip” fed automatic pistol that I can recall is the Mauser broomhandle, which uses 10 round stripper clips in a fixed box magazine.
On a handgun, I've seen them go up to 50 rounds with the magazine protruding out of the grip. 15 rounds is most common 9mm mag you will see.