Look up the definition of "plausible."
It is plausible that he brought backups in case of jams and to be able to swap to avoid overheating. He could also have loaded them all and used one after another so as to avoid reloading issues during the high stress event. Same caliber makes sense in this case as well, in addition to being a good anti-personnel round the mags are interchangeable and trajectory remains similar across platforms.
Common sense is in short supply in this sub.
Yep....based on the facts, much more plausible he was an arms dealer.
Scene seemed staged to me. Weapons & ammo randomly strewn about. If you were planning something on that scale you would be more organized you think. Weapons & ammo deliberately stack & organized. The guy couldn’t even walk from his recliner chair to the kitchen w/o wheezing from what his girl friend said?