“Very loud and quite a bit of recoil. .45 maybe?”
I read 17 rounds fired The gun appears to be a Glock. That would likely make it a .40 S&W.
A .40 Glock carries 15, the G17 9mm carries 17. Looks like a G17 to me.
17 rounds in a 40? Really? 9MM double-stack I believe. But 40? That grip looks pretty thin. Single-stack or small caliber double.
You get the following choices with a .40 cal:
Mod 23 = 13 rds.
Mod 22 = 15 rds.
You can get aftermarket factory-Glock mags, 22 rds.
There are other mags, but I don’t trust any but the glock brand.
I suggest it was 9mm.
Yeah. Its a glock. Can’t see the side well enough. But probably a 9mm or 40 sw.