The best answer is "potentially," if you are also a convicted felon. Under state law, they could argue that the bullets are some evidence that you exercised 'care, custody, or control' over the firearm.  Many times, law enforcement will only charge one individual in the car or area with felon in possession.   If you are a convicted felon, then under federal law, you could potentially be charged with mere possession of the ammunition.  Most state officers don't refer these cases to the feds because they either (1) don't know it's against the law, (2) they don't want to spend the time doing so, or (3) they really don't like the feds in their business. If they didn't arrest you on the day of the incident where your friend was arrested, then their is a good chance they are not looking to arrest you.If you are not a convicted felon, then you are not at risk of being arrest for the charge of felon in possession.  At most, you might be looking at a misdemeanor unlawful carrying of a weapon.