I have my uncle's last badge and it definitely doesn't match the number on the gun, it's 4-digits:
I'd keep the Colt if I felt more of a connection with it or if it was something really personal to my uncle but I think that he just bought it when they were issued and then put it away in a closet. He was an amazing guy and well known in his time in the department but all of those guys are long gone. My cousins when they were little girls made him this shirt so of course he had to wear it for them: