So these bullets actually went through people and hit others in the vicinity? So he didn't fire off 43 bullets?
I’m told the pistol holds 20 rounds in a “standard” magazine. He probably changed mags, but I’m just guessing. But for sure, each bullet could go through 2 or 3 victims.
Overpenetration with rounds like this are common, but hitting a second target with the same bullet is very rare.
20rnds per mag means one or two reloads if he was lucky.
A possibility, however the FN 5.7 pistol comes with 3 20 round magazines which given it’s controllability (low recoil) it’s not a necessity.
The ammo available to civilians is not geared towards high penetration compared to LEO and Military ammo. I don’t know what type he had though.