Just to give a ridiculous example, about 60 years ago I tried to shoot some 22LR in a 45-70 Springfield 1873. Believe it or not, on one attempt the firing pin actually struck the rim of the cartridge and it went off. The result was a 22 case that unfurled in a spiral configuration and a bullet that simply dropped out of the muzzle (probably the result of lowering the muzzle). It did go bang, though. I never tried to do it again, just did it to see if it would work (kids do silly things sometimes). As I recall, it took several tries before I got it to go off.
On a more serious note, I have used 38 spl in 357s and 44 spl in 44 mags frequently, as designed. I found that 32 acp chambers, fires and extracts reliably in my 432PD, chambered in 32 H&R mag. That is rather unusual. I sold quite a few Charter Arms in 32 H&R when I worked in a lgs, and none of them would do that. I discovered the ability of my 432 to do that just out of curiosity, as I had an old box of 32 acp left over from some long ago gun. Some of my customers gave me boxes of it after buying ammo at Walmart, thinking that a 32 is a 32 - I reiterated that they had to buy the correct ammo
The result was some free plinking ammo for me.
On a more serious note, I have used 38 spl in 357s and 44 spl in 44 mags frequently, as designed. I found that 32 acp chambers, fires and extracts reliably in my 432PD, chambered in 32 H&R mag. That is rather unusual. I sold quite a few Charter Arms in 32 H&R when I worked in a lgs, and none of them would do that. I discovered the ability of my 432 to do that just out of curiosity, as I had an old box of 32 acp left over from some long ago gun. Some of my customers gave me boxes of it after buying ammo at Walmart, thinking that a 32 is a 32 - I reiterated that they had to buy the correct ammo
The result was some free plinking ammo for me.