Texas Criminal Databases

Texas criminal databases
What is the criminal process?

I need to get facts about the criminal process for a book I’m writing. If the victim was shot by someone, and the victim survived but couldn’t give any details about the shooter, what would law enforcement do? In the book, I started to write about how they looked at the bullet and determined what kind of gun it came from. How possible would that be? And if they were able to determine what gun it came from, would they just look into the database and see everyone who had that gun? It’s set in Texas, where you don’t need a permit or license, and you don’t need to register with law enforcement. I just don’t want to make the case so ridiculously impossible. I want it to be something that could actually happen. Anything would help, really. Thanks.
In response to the first question: of course I’m gonna buy a gun. I’m a former Marine, a gun finatic, and an author. I figured I’d combine the two. So do you have an answer to the question?

Interesting that your last question was asking how to go about buying a gun.