"Sounds like he needs to use a larger caliber, though."
As he shot 15 rds (w/o reloading) he must have used 9mm. We are not told how many shots he placed on the target (remember these cops in NYC few yrs back?- 41 shot, 19 hits.) If his shooting was anything like that, he needed large capacity. As for 9mm, HydraShock (147gr) is pretty decent, especially from >6" barrels (or in "+P+").
True, we do not know how many shots he put on target, and yes, he was probably using 9mm. As to the merits/dismerits thereof, I refuse to get involved in religious arguments. ;-)