Does Columbo carry a gun?

All Columbo fans know that Columbo doesn't carry a gun, but from time to time the question comes up if he's EVER carried, or fired, a gun in the show. The answer is...yes, but not often.

How do we KNOW Columbo doesn't carry a gun?

Yes, an LAPD detective would probably have been required to carry one but probably the best evidence that he didn't was in Undercover when his Captain authorizes him to go undercover to find the missing puzzle pieces, and hands him a pistol - ordering him to carry it. Columbo protests, but to no avail.

In Death Lends a Hand he passes through the metal detector without setting it off. The surprised Brimmer agent suggests the detector might not be working, and asks Columbo "You're carrying a gun, right?" Columbo replies, matter of factly, "No."

In Forgotten Lady Lieutenant Flaherty comes to order him to the pistol range and Columbo says "But I don't have a gun. It's downtown." That suggests he put his department-issued pistol in his locker and just left it there. At the least, he clearly isn't carrying it.

Shooting the sand in Playback

To make the point that Elizabeth's door could have been opened by a gunshot, Columbo fires a gun into a box of sand in Harold's office.

As far as I know this is the only instance where Columbo actually fires a gun on camera.

Brandishing...but not firing, in Undercover

In Undercover Columbo's boss makes him carry a gun, and it does come in handy when Burt Young tries to double-cross him at their meetup.

But he never fires it.

Likewise in No Time to Die...

At the end of No Time to Die, Columbo carries a gun when they're storming the cabin to rescue Melissa. But he never fires it, or even points it at anybody.

What about Troubled Waters?

When this discussion comes up somebody inevitably suggests that Columbo fired the gun into the mattress in Troubled Waters. Nope, he had Danzinger do it. 

"Would you mind? Firing the gun into the mattress? I hate guns, besides I'm a bad shot and liable to miss."