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penetration

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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penetration

Unread postAuthor: dilweed » Thu Dec 18, 2008 9:16 am

okay this isn't a very serious topic, but i was bored. Today i got this crappy little hand held bike pump and attached it to my airgun. Since i have a small chamber and the pump sucks, i can only go to 18 psi(im not weak!!). I lined up 5 magazines, 3 layers of 0.5 cm cardboard a gap of 4 inches and a large book at the back.

I cocked my SPRING LOADED ball valve mechanism back on to low power setting(hard to pull back) and loaded my .177 barrel with a homemade pellet. Its a warhammer ork boyz metal stick grenade with the "stick" part sawn off and the front filed into a rounded point. I pumped it and fired at a distance of 1 inch from the first magazine. It went through the five magazines(305 pages to be exact) through the card board and went through 23 pages of the last magazine, bounce out, ricochet around in my room leaving diagonal slahes and dents in my walls( dont worrey theyre small and my parents wont notiice them) and stoped when it smacked me in the back of the head( didn't hurt much). Not bad for a "crappy spring loaded ball valve pellet gun." And check this, it slowly rotated side ways while going through the magazines.

Unluckily for me i decided to add 3 more really good rubber bands to the mechansim to pull open the ball valve, fired at the same target with a stabalized piece of ammo and now have a hole in my wall with a radius of 6 mm. I realy am dying to put some pictures on this site and learn proper grammer and spelling (lol), but i have to wait a bit. Still a promise is a promise and i put a lot of work into my gun. How much penetration can your gun do with the same caliber, pressure, target and a 12-16 grain pellet with no stabalization? Eager to hear your results.
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Unread postAuthor: cheeseboy » Thu Dec 18, 2008 11:38 am

that's a good result! at 18Psi my gun wouldn't bee able to do that (made of copper, not meant for low pressure) so I cant' help on the stats :(
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Unread postAuthor: jackssmirkingrevenge » Thu Dec 18, 2008 11:42 am

That sort of penetration at just 18 psi, unless you had a ridiculously long barrel and large chamber, sounds a bit unlikely to me.
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Unread postAuthor: Ragnarok » Thu Dec 18, 2008 12:07 pm

To slightly alter one word in a "Men in Black" quote: This definitely rates about a 9.0 on my bull-s**t-o-meter.

There is no way in hell an 18 psi cannon would punch through "305 pages, 5 sheets of cardboard, another 23 pages, then bounce back and ricochet around the room"

Firstly because it's too much, secondly because anything that penetrates it's target WILL NOT bounce back.

Sorry, but I am calling absolute and total BS on this unless I see a video and/or pictures.

As they say: "Pics or it didn't happen."
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Unread postAuthor: dilweed » Thu Dec 18, 2008 2:11 pm

the slug was side ways when it hit the last magazine, and the 23 pages is really a dent, I used 10 REALLY STRECHY ELASTIC BANDS AND ONE SPRING to open an oild ball vlave, with good flow, a 26 inch long .177 cal barrel, A 1/4 of an inch width copper pipe for the chamber with an overall length of 43.7 inches
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Unread postAuthor: Ragnarok » Thu Dec 18, 2008 2:26 pm

Sorry, I'm not buying it, especially without pictures.

I've just modelled that with optimistic characteristics, and even then I'm getting velocities that are no way up to the task.
Even if I use 10 times the pressure you're claiming, and infeasibly good characteristics, it's still not even enough to match up to my air rifle.

If I were to take my air rifle which fires a much more energetic and denser lead pellet travelling stably, I'd be lucky to get that amount of penetration alone, and certainly no ricocheting around the room.

This forum is full of people who know their stuff. If you make a claim that's as patently ridiculous as that one and you have no evidence, you will get called up on it.
In cases like these, it's best to admit you're lying as soon as possible, then you might actually get some credibility back.
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Unread postAuthor: CpTn_lAw » Thu Dec 18, 2008 2:47 pm

...With 305 pages plus carboard, at 18 psi? i'm afraid your gauge is broken mate. I couldn't do this with 300 psi in my gun. Unless you shoot with some sort of pneumatic ramrod that would cause a diesel effect.....this is BS. You are talking to people with a lot of experience in the domain of spudgunning and certain with fireamrs experience. I think 18 psi isn't enough to achieve what you claim, maybe a video could be given as a proof of your good will.
My air rifle which currently shoots at 1400 fps...doesn't do that kind of damage, even with a homemade 10 grains steel-tip pellet. (and that is heavy for a .177).
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Unread postAuthor: Ragnarok » Thu Dec 18, 2008 3:09 pm

CpTn_lAw wrote:My air rifle which currently shoots at 1400 fps... a homemade 10 grains steel-tip pellet. (and that is heavy for a .177).

That's a pretty performance for a .177" rifle - is that the one you were getting to diesel?

I reckon you could manage the penetration half of that without too much trouble. Son't forget, magazine paper is usually a lot thinner than regular paper. I've done a lot of testing, and wouldn't be too surprised to get through about the numbers he's claiming with my TX200, but it'd be more than I'd suspect.

My TX200 only does about 800 fps with 8 grain pellets (nominally 7.9, but my scales find most weigh closer to a full 8.) I could tune it up to do more, but there's a number of reasons I don't - that I don't want to damage it, don't need to do it, and rather want to keep it legal.
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Unread postAuthor: jook13 » Thu Dec 18, 2008 3:10 pm

Maybe your guage reads 18 bar instead of psi?
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Unread postAuthor: jonnyboy » Thu Dec 18, 2008 3:11 pm

Bs there's no way that a spring triggered ball valve can go through that much material at 18 psi. My commercially made air gun couldn't do this so there's not a chance this is true. I'll only beleive his if you can repeat this on video.
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Unread postAuthor: starman » Thu Dec 18, 2008 3:13 pm

Just a curious observance. Why do some of you guys often preface dubious ventures like this with I was bored? This "I was bored so I..." usage seems to be a fairly modern cliche used when you want to indicate motivation to actually do something. It seems actual boredom may or may not have anything to do with it since your thought process was obviously in gear or you were being inspired by something you saw or read...not usually indicative of a bored state.
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Unread postAuthor: Ragnarok » Thu Dec 18, 2008 3:13 pm

jook13 wrote:Maybe your guage reads 18 bar instead of psi?

In a hand held format, only a shock pump would be up to that, and I kind of suspect that he would know if that's what he had.

Even if that is the case, it would still be very optimistic performance for even 18 bar.

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starman wrote:Why do some of you guys often preface dubious ventures like this with I was bored?

Boredom is a very serious motivation for today's youth.

I have suddenly been struck by attacks of boredom, then decided to go and do something with the time to try and alleviate the ennui.
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Unread postAuthor: dilweed » Thu Dec 18, 2008 3:22 pm

im sorry you guys think im lying. Mybe some more informaton would help. The pellet tip is very sharp(homemade), has a cylindrical body with a length of 8mm. The actual release of the air is blocked out by the clanking noise my mechanism makes. When the trigger was pulled the mechanism was on a HUGE amount of stresss due to the elasic bands( theyre not the red thin kind) and completley broke. I fire the bullet at the editions of the magazine called the week. It's a not very strong paper( thinner than printer paper.) And i have thin walls in my house. the pellet ricoched and hit me with very little power. I think my pressure gage was slightly wrong, because the results were miniscule compared to the average test of 240 psi. 240 psi with a 1/2 inch ball valve is REALLY LOUD.
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Unread postAuthor: Ragnarok » Thu Dec 18, 2008 3:33 pm

The most important thing you can do now is provide photos, or far better, video evidence.

Without this, you're not going to sound convincing, and it will just seem like you're trying to dig yourself out of a hole.
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Unread postAuthor: jackssmirkingrevenge » Thu Dec 18, 2008 3:39 pm

CasinoVanart wrote:IDK, remember the thread about the guy piercing a coin with a crappy ball valve pneumo? I called BS on that one, so did many others


True, however that was something no one here had tested. I've made enough small calibre piston launchers to know the value of high pressure, and there is no way that one chan achieve that sort of performance at 18 psi.

Videos proving me wrong would be most welcome :)
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