I collect antique firearms. It has not been my experience that sellers generally test-fire an item before selling it. More common is a disclaimer that if you want to shoot the thing, you should have it inspected by a qualified gunsmith familiar with the particular model.

No, they don't. Unfired weapons fetch a premium. For true antiques every time you fire it is another opportunity for it to break. These are not weapons that are valued for "working".

Firing an antique firearm decreases the value. It is now used.

Really depends on the gun to some degree. There’s collectibles that are worth more left alone, especially old stuff pre modern ammunition. But lots of old but not that old stuff its more or less expected you’ll fire it to test it works on receipt.

"old but not that old" is essentially saying it's not an antique.

There are plenty of guns running around that are over 100 years old that are surely an antique by anyone's definition, but are safe and reasonable to show with modern ammo. Pretty much any gun of that age, unless it was some kind of commemorative thing from the start, is going to have plenty of rounds through it already.

For example - an M1903 is an antique by any definition, and you'd be hard pressed to buy one today that's unfired.

If I buy a WWI-era pistol, they’ll fire it before I fork over the cash? Surely not, right?

Only if they are claiming it still works and are asking for more money due to that. And still, only if you care enough to verify it works as they claim.

Why not? There are people out there that manufacture their own ammunition. This wouldn’t surprise me at all.

What about a 17th century dueling pistol?

I think in this case anyone would be wise to fire a modern reproduction rather than the original article. After all anyone with the money to collect that sort of artifact can certainly afford a replica to play with.

...And modern replicas tend to be safer when you pull the trigger.

Well, if you count making a new stock and barrel to mount the original 17th century clockwork gubbins to, may I present:

https://forums.somethingawful.com/showthread.php?threadid=40...

the GP's example of WWI is actually sufficiently modern that you could very well just be firing normal center fire .45 which is readily available https://en.wikipedia.org/wiki/.45_ACP

That would depend.

As a buyer, you would need to decide for yourself whether you want a guaranteed working firearm or not.

And in many cases, the owner will test fire the firearm before putting it on auction anyway.

Old Martini Henri rifles, dueling pistols, even muskets in some cases.

It depends, but the general rule is that the older it is, the less people want to see it in active use. At some point it's about preservation over anything, but there's also the safety concern! A firearm is a very dangerous thing in failure mode, so at some point a firearm is both too historically valuable, and too damned dangerous to fire.

Source: Forgotten Weapons and Royal Armory youtube channels

Why not?