Police are charged with enforcing the law and while they should know the statutes they enforce, they sometimes have a... well, to keep it on the High Road, we'll call it an imperfect understanding of those statutes.
From the lowliest beat cop to the Chief of Detectives, their mission and mandate has absolutely nothing to do with giving out legal opinions, and any opinion you might recieve would be of no value in court. Just try mounting the "Officer Krupke said I could" defense in a felony trial and see how far it gets you.
If you want to base your actions on an interpretation of the law, get that opinion from the Attorney General of the state whose statutes you might find yourself crossthreaded with. Get it in writing. This is still no guarantee that you won't find yourself in court over it, but it's your best basis for a defense.
Here in Missouri, until last year, purchase of a "concealable firearm" required a permit from the county Sheriff and was only available to those 21 and over, and our CCW was only issued to those of at least 23 years of age - although we recognize all other states' permits regardless of residency.
A bunch of "gunforum lawyers" figured out that this didn't apply to C&R firearms so only the federal law of "18 years old, gift or private purchase" was relevant. Also, a Maine non-resident CCW permit could be obtained at 18 years old. So... in theory, Billy Bob Highschoolsenior could, legally, obtain and carry concealed a Broomhandle Mauser.
In practice however, the first time he got "Terry Frisked" Billy Bob would be taking a ride to the Grey Bar Inn. About the only thing that could be counted on to lubricate his almost certain passage though the legal system would be a signed and dated affirmative opinion from the AG, assuming one could be had.
All this to say; be very careful with the legal aspects of the shooting sports at your age. Just because an act may be technically legal, doesn't mean it still won't cause you a world of trouble. If your actions are righteous, you shouldn't have to worry about any long term ill effects, but anytime you have to disprove your guilt... er... I mean, confirm your presumed innocence, it usually takes a bucket full of cash.
Shoot well and be safe,
Joe