There are problems with the assassin scenario. What if he was caught in the act, then Jeremy is fucked. There would also be someone who could come back at any time in the future and cause him hassle. An assassin may have had qualms about killing two young boys in their sleep. One was shot in the back of the head and the other in the face while he was sucking his thumb. If the assassin couldn't complete the job then they would inherit half the wealth and Jeremy wanted it all without future comeback.....I could certainly go with an assassin type who has no compunction about taking out the kids. I seriously cannot see Sheila or even Jeremy doing that......but....but. This is the issue. I don't know him nor Sheila, nor the dad.
What's to say there isn't a massive twist in this carry on. A twist that's maybe so far out as to never warrant a thought.
The only person he could rely on was himself. Personally, I'm more inclined to believe he took another pre-loaded magazine which he disposed of afterwards.
25 shots were fired and 30 left in the box that originally contained 50 so where did the extra 5 bullets come from.