To more accurately answer your question it would help to know what you were charged with. If you are charged as a felon in possession then it doesn't matter if it was stolen or not. As an experienced criminal defense lawyer one thing that all felons know is that they cannot possess a firearm. If you are charged with concealing or receiving the gun as stolen property typically the government need only prove that you knew or should have known based on all of the circumstances that the item was stolen. Hope this helps.
You can be charged with receiving stolen property if you are in possession of property that you knew was stolen. Having a statement from the person who have you the property may help your case, depending on the facts of your case. You should speak to a criminal defense attorney about the possible defenses in your case.
Whether those selected facts would provide a viable defense would in part depend upon the crime charged. If the crime was possession of stolen property, evidence that the accused did not know it was stolen, nor had reason to know, would be helpful for the defense.
It sounds like you may have some legitimate defenses; however, I would advise you not to speak with the police, or anyone else other than your attorney. Even if you are charged with a crime, this does not mean that there is enough evidence to convict you (probable cause for an arrest is a much lower standard than beyond a reasonable doubt for a conviction).
I hope you find this information helps.
Best of luck to you,
Leone Legal, PA
Licensed to practice law in the states of Minnesota and Florida