You have to be proven to have malicious intent to get jail time. Like i posted about, it happens about 7000 times a year in the US. Many dont even get arrested, but it is MA afterall. Usually a fine and some kind of program, with what is generally considered to be the worse outcome, is losing your ability to own a firearm. They tend to be more lenient with High net-worth and public figures, which believe it or not, has happened countless times before. Again, not saying he gets a pass, but he aint going to jail. Not a chance unless there is more to the story. The vast majority of these cases get thrown out.. Same thing happened to Mike Epps about 3 months ago.
After reading about it, he was probably arrested because of the extended Mag which is illegal in MA. Depended on where he was traveling to, and where and if his guns were permitted, that's what could be his undoing. You can also buy a gun in another state with the intent to get it permitted in another state. There's often a grace period in states that require you to have a license in the first place. Remember, this is the United states, not Australia.