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An accident that almost happened with an 'empty' gun.

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An accident that almost happened with an 'empty' gun.

Unread postAuthor: boyntonstu » Wed Oct 07, 2009 5:34 pm

I was testing my latest piston mod and as ALWAYS I kept the muzzle pointed to a safe place in my garage.

As the pressure rose past 300 psi it fired!

But there was no projectile loaded.

What the hell was shot?

This is what happened:

The sealing washer was held to the Oak piston with a sheet metal screw and a washer.

The 300 psi got under the washer and forced it and the screw out of the barrel.


Lesson learned.

Now back up a little.

I noticed a slight leak, and I suspected that air could get under the washer and passed the screw threads.

I used hot glue to make it seal better.

Not good enough.

Solution: I counter bored the oak piston and used a machine screw, nut, and a washer to mount the rubber washer.

Remember, NEVER point the muzzle of any gun to anything or anyone that you don't mind shooting.

There ain't no such thing as an empty spud gun.

BoyntonStu
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Unread postAuthor: theBOOM » Wed Oct 07, 2009 5:36 pm

Well.. there is now such thing as an empty pneumatic or hybrid spudgun ...
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Unread postAuthor: Ragnarok » Wed Oct 07, 2009 7:09 pm

You should bear in mind that even the muzzle blast from a spudgun can be dangerous. It's still several grams of gas travelling at a few hundred metres per second - so frequently, it's as energetic as the projectile (if not more).

Personally, there's a reason why my spudguns are fitted with a "hard" safety. Simply disabling the trigger isn't enough to be sure, so I've got a ball valve sitting in the way of the main valve's barrel port.

http://i210.photobucket.com/albums/bb12 ... P01173.jpg

The ball valve immediately to the right of the piston valve is the this main safety. If that's on, nothing short of the launcher blowing apart can cause it to fire - whether or not you want it to (and yes, there have been a few situations where I've accidentally left it on when I've pulled the trigger.)

Others have tried to tell me that it's unnecessary, but as far as safety is concerned, chances should not be taken... which is why you can see a trigger/fill safety on the right of the trigger valve.
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Does that thing kinda look like a big cat to you?
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Unread postAuthor: c11man » Wed Oct 07, 2009 9:57 pm

i had a similar accident happen with my qdv. while doing some of my first shots the hadle was not secured properly allowing it to slide of the rod slightly. this made the piston move ahead more that it should and at aobut 100psi the piston became the ammo and shot up through the ceiling and into the attic.
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Unread postAuthor: Technician1002 » Wed Oct 07, 2009 10:38 pm

c11man wrote:i had a similar accident happen with my qdv. while doing some of my first shots the hadle was not secured properly allowing it to slide of the rod slightly. this made the piston move ahead more that it should and at aobut 100psi the piston became the ammo and shot up through the ceiling and into the attic.


I had a close call with the t shirt cannon, but the rod, nut and pin on the rod and in the golf ball held and did not eject the piston. It did blow forward and bleed off the air out the back.

On the Marshmallow Cannon, Closing the valve too fast tended to set the valve too far forward and it would blow forward when air was added, but this movement always happens early at low pressure so the valve never ejected.

I drilled a hole in the side and put in a pin so that launcher can't do that anymore. I did that just before it was lent to shoot t shirts so there would be no liability accidents. The primary reason was for reliability so the valve would close properly every time so the people that borrowed it would not have to wait for the pressure to bleed off to re set the valve. Safety to eliminate the possibility of an ejected piston is a secondary benefit. For me it is obvious to stop adding air when it was hissing out the back when filling.

Edit; added pictures.
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Attachments
piston retention1.jpg
A welding rod was bent and the ends pushed into a pair of holes. There are no sharp points outside. Yes the piston end rests this far forward for a small dead space.
piston retention2.jpg
The piston normally stops just short of the pin, but if someone slams the valve closed it hits the pin, still too far back to unseat any o ring.
Last edited by Technician1002 on Thu Oct 08, 2009 12:36 pm, edited 4 times in total.
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Unread postAuthor: jackssmirkingrevenge » Wed Oct 07, 2009 11:22 pm

theBOOM wrote:there is no such thing as an empty pneumatic or hybrid spudgun ...


That was my first thought when I saw the title of the thread, the importance of muzzle awareness cannot be overstated.
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Unread postAuthor: MRR » Thu Oct 08, 2009 10:50 am

A "hard" safety like Rag described makes perfect sense, especially when you have a muzzle loader. I use them myself (on my newer models) because of the strange feeling to load a pneumatic from the muzzle @250 psi.

Once I loaded a gun before I pressurized and at about 200 psi the hose of the pump burst and vented the pilot.

A 16cm nail dart went right through a cupboard.
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Unread postAuthor: boyntonstu » Thu Oct 08, 2009 12:10 pm

MRR wrote:A "hard" safety like Rag described makes perfect sense, especially when you have a muzzle loader. I use them myself (on my newer models) because of the strange feeling to load a pneumatic from the muzzle @250 psi.

Once I loaded a gun before I pressurized and at about 200 psi the hose of the pump burst and vented the pilot.

A 16cm nail dart went right through a cupboard.


WHAT!!!!???

the strange feeling to load a pneumatic from the muzzle @250 psi.

DON'T DO THAT AGAIN!

Never load a pneumatic after pressurizing.

I added a Schrader valve to bleed the chamber if I decide not to shoot a loaded round.

Please, we want you in good health on the forum.
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Unread postAuthor: MRR » Thu Oct 08, 2009 12:25 pm

Haha, that "strange feeling" thing was a joke!!! :lol:
Do you think I'm nuts?

I should use more emoticons though.

After the incident with the nail dart I started to use breech loads and safety valves.
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Unread postAuthor: Brian the brain » Thu Oct 08, 2009 12:44 pm

anyone that you don't mind shooting.

:shock:
Seriously... :roll:


It seems like we all need these close calls early on to keep us safe in the future somehow...

Thanks for sharing this!
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: psycix » Thu Oct 08, 2009 3:18 pm

because of the strange feeling to load a pneumatic from the muzzle @250 psi.

:lol:
Yeah, feels weird doesn't it?
Some people call it common sense, or "fear". It can be rather uncomfortable, especially when looking down into the pipe to check if the projectile is still okay after ramming. Dont forget to grab a flashlight.
If you feel unsafe while staring down the barrel, let some air out of the pilot to lower the pressure.


EDIT:
For safety reasons, I'd like to add: the above is a joke. NEVER do it, its useless and extremely dangerous.
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