Suicide?

After having breakfast, Max and the others visited Jimmy in the hospital to ask him a few questions. 

Unfortunately, it wasn't very productive since with a mentality of a two year old child, they didn't get an answer to any question. All they got was random gibberish. 

But one thing to take note of was the fact that Max discovery Jimmy suffered from Essential tremors.

Essential tremor (ET) is a neurological disorder that causes your hands, head, trunk, voice or legs to shake rhythmically. It is sometimes even confused with Parkinson's disease.

As a result, Max saw that Jimmy couldn't even hold his toys and snacks firmly in his hands, let alone a gun with a powerful recoil. 

This he came to the conclusion that it's impossible for someone like him to continuously shoot three rounds of fire back to back and all of them actually hit on mark at that too.