[lobo24]

Need to check used gun and find true owner and past owners

[AK lawyer]

Good question.

It appears that there are several databases maintained by the BATF.

"... Nevertheless, the ATF Firearms Tracing System (FTS) contains hundreds of millions of firearm tracing and registration records, and consists of several databases ..." Firearm Owners Protection Act - Wikipedia, the free encyclopedia

At the ATF website, there is some useful information, including this form , which suggests that only an ATF agent may access the databases or make a records request.

[ScottGem]

Take the gun to your local police station and ask them to do a trace.

[AK lawyer]

Take the gun to your local police station and ask them to do a trace.

Yes. But keep in mind, one should be very careful in taking a gun into a police station. :)

Might be easier to write down the make, model, and serial number, and for good measure take pictures of it.

[ScottGem]

Good point. Maybe making an appointment before hand would be a good idea.