I know this sounds dumb and stupid. But kind of curious.

Could you fire off a round (say 9mm) by holding the case with leatherman pliers and hitting the primer with a punch pin (like the keychain rescue window breakers or a spring loaded center punch)? If so, could you be somewhat effectively defensively with it (say, single shot, close quarters)?

No, there's nothing to contain the pressure from the gases of the burning powder. In your scenario, the case would be what gets propelled away from the bullet.

Yes, you could ignite a round that way. However, as noted, most of the uncontained pressure goes to blowing out the case, with only a fraction of the energy left to actually drive the bullet. You might lose even more due to unburned propellant.

You could get someone's attention, but I don't think you could get much of a defensive strike. You'd also likely get a faceful of brass shrapnel.

The primer will probably blow out and shoot your eye out.

Thanks guys! Curiosity settled.

Even the video above is biased against what would probably happen. It has the cartridge held firmly in place with no give. The case head is held and enclosed. Outside of the jig, if you could hold it well enough, as mentioned the primer would come out. In say a fire, with nothing holding it, the primer may stay in because the whole case head goes flying (seen it both ways).