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# Primed .22 cases? Answered

Would the primer go off on a .22 case that has had the bullet and powder removed if you shot it with a 900 fps .177 lead pellet? Also, would it go off if shot from a slingshot at a brick wall.

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as a shallow youth, i threw .22 rounds at the pavement and got them to ignite.

now i realize the inherent danger in this. but it can be done.

I'm going to guess that both those scenarios have a some probability of success. And that guess is based on following model:

1. There is some minimum amount of energy needed to activate the primer.
2. You have to deliver this energy to a physically small area; i.e you have to crush a small spot on the cartridge. The area of this spot is just a few square millimeters.
Normally this action of crushing a small spot on the cartridge, is accomplished by way of a firing pin
http://en.wikipedia.org/wiki/Firing_pin
and a spring loaded hammer. Sometimes the firing pin and the hammer are the same piece of metal.  In any case, the goal of the firing mechanism is to deliver energy to that tiny little spot under the firing pin.

22LR is a "rim fire" cartridge, and it's initiated by crushing a small spot on the rim.  If you have spent 22 shells, you can look at them and see the little dent where the firing pin hit.

Back to the subject of work and energy:  How much energy does the firing pin transfer to the cartridge?

Well, it's a number that's less than or equal to the energy/work required to "cock" the gun, i.e. to pull back the spring.  And that's a relatively small amount of energy
http://en.wikipedia.org/wiki/Work_%28physics%29
It takes a lot more work(energy) to pull back a slingshot, than it does to cock a 22, and I'd expect a 22 cartridge launched from a slingshot would contain a lot more kinetic energy
http://en.wikipedia.org/wiki/Kinetic_energy
than a swinging firing pin.

However a problem that might come up when launching a 22 cartridge from a slingshot, is that the bullet end might impact the wall first, and steal most of the collision energy away.   Of course you want the side with the primer to hit the wall, and hit on the rim

This is a really bad idea, you know.  Because it could result in firing a bullet, and maybe pieces of the cartridge, in unpredictable directions.

Shooting a cartridge with a pellet gun is really dumb too, for the same reason:  a bullet, or bullet-like pieces fired in unpredictable directions.

Anyway, for both those scenarios, you have way more energy than you need. The only other requirement is hitting the cartridge in the just the right spot.

Of course the easiest, and safest, way to do this is by using a gun designed to take 0.22 cartridges.  Less safe, yet more sane than ideas you've suggested, would be building something that approximates the same mechanism: hammer, firing pin, etc; i.e. make your own gun. Building your own homemade gun is still kind of a bad idea, but not nearly as dumb as trying to set of cartridges by shooting them, throwing them, etc.

BTW,  please try not to end up putting any holes in yourself, or others. Because that sort of thing can happen when trying to fire cartridges in an unconventional manner.

They are not complete cartridges, only casings with primer. Powder and bullet is removed.

Thanks for the clarification. I think I might have misread this question from the beginning. Anyway you're right. Without the bullet and powder, this trick is much less dangerous. Good luck with your efforts to make things go bang!

If you have seen a fired 22 rimfire case, the firing pin leaves a deep notch on the edge of the rim. It takes a fair bit of force to crush the rim and set of the primer.

Would it go off if you shot it with a pellet gun? Quite possibly. Would it go off if you sing it into a wall? I would say no, But still a possibilty.

Try it and see. It isn't very loud, and it's safe to do as long as there is no bullet in it.

Okay, I'll try it tomorrow and post back.

Slingshot No. Pellet gun yes :). Did make a bit of a bang, especially inside the basement.

> it's safe to do as long as there is no bullet in it.
.  My experience is that there is enough energy in the primer to cause the very light casing to move across the room at pretty high speed. Probably wouldn't do much damage if it hit a fleshy area, but you might put your eye out. ;)

I used to put a live shotgun shell into sand ( the cap just showing ) and
then shoot at it with a ( cock only type ) BB rifle from behind a giant log.

When a BB hit the shell just right there would be a pop and the empty
shell would sail over my head.

A

Primers are shock-sensitive, so "I would think so".
Why don't you test it and find out?

L

Anything that will bend the rim can set off the primer.

I would think so...