I am going to assume the M9 is a military issue firearm.If the M9 is a full-auto version, illegal possession of a unregistered machine gun and failure to pay transfer tax on same.Felony possession of stolen government property. There is no such thing as a state-level crime on a Federal installation. Everything is a felony.You as the civilian get off easy. You simply get a felony conviction and if youu2019re lucky, a massive fine and probation. Given that it would be a firearm from a military facility, donu2019t be shocked if both the military investigator recommends prison time to your State Attorney General. My understanding is the military does not have a sense of humor or moderation when it comes to theft of stuff that goes u201cBang!u201d or u201cBOOM!u201d from their armories.It goes without saying your life opportunities and career options as a convicted felon will be severely limited afterwards.The soldier, on the other hand, will wish they had never been born. A stint at the Disciplinary Barracks at Fort Leavenworth followed by fines and dishonorable discharge is the result. This is not a cakewalk and the aftermath will follow them for the rest of their lives just like civilian convicted felons with the added bonus of a DD-214 dishonorable discharge coming up on every background check that will ever be processed on you.Watch doors slam shut. You wonu2019t even work as a McDonaldu2019s cashier after that.I hope the M9 is worth it for the time you have it because you wonu2019t have it ever again in the wreckage called your life post-conviction.