Have your co-worker ask his dad about the rifle. In the long years between common use of cartridge rifles and WWII (during which production of tons of stuff was dropped and never restarted), there were quite a few "parlor" rifles.
These are break action, or falling block guns, usually, intended for short range target shooting (indoor target practice AT HOME was popular for some time waay back then), and pest control.
There were .25 and .32
RIMFIRE rounds back then, as well as a host of other chamberings. My Dad had a falling block .25 rimfire, although we never shot it, because there was no ammo available.
I think what is most likely is your co-worker's father has a .25 rifle he
thinks is chambered for .25acp, (and one where a .25 auto might even go in the chamber), but the odds of it being actually chambered for .25 acp are slim.
I have learned to never say never, as it is always possible someone, somewhere, sometime had a barrel made for .25acp. I have considered getting one for my Contender.
As to a modern (post WWII) factory rifle in .25ACP, I have never heard of one, or seen one cataloged. Considering the towering status of the .25ACP, a rifle in that caliber would still be inferior to a .22LR for game, and way ahead, even today, for ammo cost.
If it turns out he actually does have a rifle, factory made in .25acp, we'd love to see it.
I heard about the .25ACP Tommygun, too, but I understand that was a custom made one-off.
