what you're saying about him doesn't match with your character's bio. caliber switching through foster homes, jail cells and having no family after the age of 6, where does your character find the time to research weaponry up to that caliber? remember, you have to follow character, not yourself. get your story straight, man. technically, based on your character's bio, your character barely had enough time to learn his trade, let alone take up a hobby. because the old man sure as hell wasn't teaching you, since his intent for coming into our time was to find, raise and prepare us for this adventure.
in short, you keep making your character too powerful/smart/savvy.