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Boosting pellet rifle performance

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Unread postAuthor: imjustpk » Fri Apr 06, 2007 2:06 am

I'm sorry but can someone help me understand the physics behind dieseling? I tried to look it up, but on the net all it wants to describe is car engines. Also CpTn_lAw, I see your equations, but I don't quiet understand them with only the letters/abbreviations. I know it is a lot to ask, but this dieseling effect sounds amazing. It makes me all tingly to think of the possibilities.
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Unread postAuthor: CpTn_lAw » Fri Apr 06, 2007 2:41 am

Ok i'm going to explain:
the equation P.V = n.R.T is the equation of perfect gazes.
(Pressure) x (Volume) = (number of moles of matter) x (Constant) x (Temperature in Kelvins)

So basicly, The piston is released. The spring behind pushes it very fast. At a certain point, the piston enter a closed cylindrical tube, of which the only escape is behind the pellet. The piston goes further, increasing the pressure as fast as it decreases the volume of the chamber. Globaly, this multiplication grows. the other side, n is constant because you don't pump, it's the same quantity of air as in the begining. R is a constant, so the only factor that incrases is T in kelvin. (0°C =± 273.15 ° K)
At the point where the pellet is forced through the barrel, the volue is critical, the pressure maximal, and the temperature is instantly very high.
High pressure + High temperature ignites certain substances automaticly. Like diesel fuel in engines that run the same simple principe.

So I anaged that if something burns inside, anything with a high burning rate would explode. I used it to gain performance. The pressure increase dramaticaly when the mixture burns, pushing the pellet way quicker out of the barrel. (It makes a lot of residutes inside the barrel)
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Unread postAuthor: Hawkeye » Fri Apr 06, 2007 9:25 am

It doesn't take much pressure to increase the temperature of compressed air to the point where it will ignite flammable material.
Look at how easily a fire piston ignites tinder on a short plunger stroke powered by a human arm.
If I seal the end of my homemade high pressure pump with my thumb and rapidly push the handle there is the sensation of pinching out a candle flame.
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Unread postAuthor: imjustpk » Fri Apr 06, 2007 10:35 pm

Oh okay. Thank you very much for taking the time to explain that, now all I have to do is try to aply this all to spud gunning.
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Unread postAuthor: CpTn_lAw » Sat Apr 07, 2007 3:32 am

You're welcome, it was my pleasure to help you!!
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Unread postAuthor: LucyInTheSky » Tue Apr 17, 2007 7:56 am

EDIT: sorry didnt see the other 2 pages lol

Jack, I have a the same air pistol as the link you posted, its crap but i will be deseiling it lol.

Your HW97 looks good, i have a '35 myself and think i could club a bull to death with it and there not be a mrak on the rifle as it so heavy and solid.

It would have to produce ALOT of pressure to reset the spring as there was about 1.5" of the new spring sticking out of my rifle when i was puting it back together and I had to lean my whole weight on it just to push it down, then i slipped and cut my arm open lol.

WD-40 apparently deisels well, as when i bought my rifle i though i would lube it up see it i could increase performance but once i had donethat, just to test it i fired it at some yellow pages and it went all black...
Image

EDIT 2: I think shooting through road signs i pretty damn powerful.

Plus you can get rapids with produce about 80ft-lbs thats 108J i think.
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Last edited by LucyInTheSky on Tue Apr 17, 2007 8:06 am, edited 1 time in total.
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Unread postAuthor: CpTn_lAw » Tue Apr 17, 2007 8:05 am

well, i don't use oil to boost performance. you do must have a cleaning kit for the barrel, with brass brush to clean the barrel. Combusting effet does a lot of residutes. and btw, i don't have a HW97, i have a gamo Shadow 1000
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Unread postAuthor: jackssmirkingrevenge » Tue Apr 17, 2007 9:02 am

Plus you can get rapids with produce about 80ft-lbs thats 108J i think.


That's nothing, in the power-mad US of A you can get custom pneumatic rifles like those built by Gary Barnes that exceed 500 ft/lbs.

Not to mention this custom 20mm monster:

Image

Image

That's a 1005 grain pellet fired at 715 feet per second to give a massive 1,140 ft/Lbs, that's roughly the same as a 3 round burst from a submachinegun :shock:

i don't have a HW97, i have a gamo Shadow 1000


Believe me, if you did, you wouldn't commit the sacrilege of attempting to encourage dieseling :roll:
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Unread postAuthor: judgment_arms » Tue Apr 17, 2007 9:21 am

Hey CpTn_lAw, first, wouldn’t that thing be illegal?
Second, before you try this again, STOP!!!! By putting fuel in a springer you signing your gun’s death warrant, if not your own! Did you check out the link Jack posted? You must not have so I’ll quote it:
Forced dieseling is NOT SAFE!
This is for CF-X guy and anyone else who wonders what can be done with a dieseling airgun. It's all been done before, and the facts are well known. Dieseling destroys spring-piston airguns. They aren't made to take the pounding of the repeated explosions. The EL54 lasted because people couldn't get the ether ampules. Yes, there are ways around that, and they have been tried - and they destroy guns, too. Shooters have been injured when their guns blew apart or pieces flew off at high velocity. This is not a road to go down. If you do, a lot is known about what will happen, and none of it is pleasant.


I understand and appreciate your quest to increase the power of your springer, but this is not the way.
Try a less destructive means, such as putting a spacer behind the piston to force it to compress more.
If you would like to increase it’s power safely head over to the Gamo Forum and ask, well your at it why not tell them how you’ve managed to increase the power of your Gamo, see what they have to say.
Now, before you get mad, I’m not trying to be mean, just keep you, and your gun, in one piece. I don’t like hearing people talk about how there gun just blew up. Even worse, I don’t like hearing it second hand because the guy who’s gun blew up can’t tell about it.
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Unread postAuthor: jackssmirkingrevenge » Tue Apr 17, 2007 9:46 am

Hey CpTn_lAw, first, wouldn’t that thing be illegal?


There's no reason why it should be illegal as far as I can see. However, thank you for reiterating the safety aspect, the forces involved should certainly not be taken lightly.
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Unread postAuthor: judgment_arms » Tue Apr 17, 2007 12:54 pm

I’m dead serious; dieseling is not something to take lightly. I’ll give you five reasons why dieseling is bad:
One, it can ruin the seals in the gun.

Two, it causes the gun to wear out quicker, particularly the spring, and piston house which was not designed to take the added pressure.

Three, when a springer is dieseling it’s accuracy suffers significantly, most guns, if not all guns, require a brake in period (generally about 500 to 1000 rounds) to burn out all the packing oil before the gun can shoot accurately.

Four, the increase in power may make it illegal were he lives, since he could only get the 660FPS model there’s obviously some form of performance cap which he’s exceeding by forcing the gun to diesel as heavily as he is.

Five, the added noise, barrel fouling, and muzzle flash would be a nuisance seeing how the only thing not being decreased is muzzle velocity.

To sum it all up: forcing a gun to diesel like this will indeed result in higher velocities, but at the cost of added wear and tear on the gun, more noise, increased barrel fouling, and a loss of accuracy, not to mention that it may make an otherwise legal arm illegal.

Oh yes, and I almost forgot, is the added velocity worth all the afore mentioned plus the add risk of the gun being damaged beyond use, and you quite possibly be hurt also. I hope you’ve got your eyes and ears on well shooting gun.
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Unread postAuthor: FeLeX » Tue Apr 17, 2007 2:20 pm

Judgement is seems you just pulled all that out of your ass. 500-1000 shots to get it to shoot accuratly again? Where the f*** did you get those numbers. If make s*** up at least do it good. Deiseling isnt even as half as dangerous as people say. If your smart enough not to put a crap load of propelant in the piston you will be fine.
My friend is shooting same all aluminum gun that he casted 2 years ago from bunch of aluminum cans. Hes still alive and so is his gun.
If you think about it everything is dangerous if you dont use it right, but if you do its all good. Take potato guns, oxy+propane potato gun that wont explode can be easily made. Thats if you put the right amount of fuel in it...
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Unread postAuthor: judgment_arms » Tue Apr 17, 2007 9:50 pm

I ain't got time for this. here:link to topic in the Yellow Forum
it's your gun, do as you please.
oh FeLeX, I own two springers, my dad owns six or more. I know what I'm talking about, I've had to break in two, and help break in at least six more. my Gamo shadow too a little over 500 (used up a 500 count tin of pellets plus a hand full of rockets) rounds to break in, and my China-gun (B3-f) took well over 1000 (whent through about five 250 count packs of Gamo hunters). one of my dad's break barrel China-guns has had well over 500 rounds through it and is still spewing smoke.
When I said 500 to 1000 round I ment 500 to 1000 rounds.
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Unread postAuthor: CpTn_lAw » Wed Apr 18, 2007 10:40 am

yeah you're right! absolutely right. My grandpa's springer did a lot of smoke even after 1000 pelets. Mine doesn't combust very well, with oil.
I'll be careful when fire it next times, and i already start planing the moment i stop shooting with extra power. I'll bring it to the store and ask for a complete clean up + piston seal and spring. as for the barrel, i already have a cleaning kit.
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Unread postAuthor: beebs111 » Thu Apr 19, 2007 12:01 am

wouldn't that decked out 20mm gun be illegal? in the U.S. anything over .5" is a destructive device, and thats .78"
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