Legal Question in Criminal Law in Texas

Re: 4th Amendment violation

maybe. Were you arrested for anything? Any charges? any evidence obtained?

As you may know, the 4th amendment protects us from unreasonable searches and seizures. The remedy for such intrusion typically is referred to as the "exclusionary rule." If you were not charged with anything, and no evidence was gathered, you likely have no fourth amendment remedy. If, however, evidence was gathered, like the gun was stolen, you might have a good argument to have that evidence suppressed.

It is not a violation to carry a weapon in your vehicle in texas unless you are committing a crime other than a class C misdemeanor. So, informing a cop that you have a gun is not a crime and does not give the cop probable cause to search for and seize your weapon.