The square is definitely better. It's more focused and nastier looking.
I once photographed an idiot who brought a gun. When I said that I could look down the cylinders, she offered to get the bullets out of her car. I said not to bother and had her point it down and it was fine.
Also, holding it improperly isn't a problem here. This isn't about how to use a gun properly. If a gang member holds you up, proper gun etiquette isn't the prime issue. Unless of course, the gang promotes gun safety and membership in the NRA.
I like the mood, even though the subject is oof you can see that there's no fear in his eyes, he's all business...he's almost emotionless. He looks like he's tired of talking or waiting and he wants his gun to speak for him. His hands are worn and knarled like those of a laborer and his life hasn't been easy. He's squeezing the gun with determination.
IMO when you critique a photo, you critique the elements of the photo, the photo tells a story in great detail if we care to look.
Its shouldn't be an argument about whether he's holding the gun right or whether it should be a .45 instead of a .38, who cares about all of that...that's not the point of the photo.
You have it all there; imagination, composition, lighting...your photo is a welcome change...