pressure 22air vs 22LR
Hi, can anyone tell me how is it possible that a .22 airgun (modified condor for example) can shoot almost at same velocity (1100 fps and more) as 22LR when using same 40grain bullets. The pressure which airgun operates is 2000-2900 psi vs pressue in 22lr chamber is arund 22000 psi. My guess would be that when bullet travels down the barrel airgun gives that 2000psi all the way to the end vs 22lr gives this 22000 psi only at the beginning, am i on the right track?
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synopsys,
Recall accepted, 😀
Here’s something to think about while Walter proves himself and me wrong with his own gun: A higher velocity might be reached with a tighter fitting slug.
Here’s the theory (first told to me by Barnes); if the slug holds its position for just a tiny time, the air pressure will build behind it so when it does slip its hold, there is more power available to accelerate it down the bore. A loose slug will move with the first rise in pressure and the bulk of the pulse will fill a larger volume.
If that sounds crazy, check out the NASA light gas gun details on Wikipedia. They actually use a 2mm thick stainless steel rupture disk to allow the pressure to grow before the projectile moves. When the pressure is high enough it blasts open the disk (the disk has been scored to open in a controlled manner and with minimum debris) and then sends the slug down the barrel at up to 7000 meters per second.
If you do the math it comes out to around 740 fps.
Man that thing had some serious muzzle flip!
How fast was were the slugs going?
What was Cygnus getting out of his 45cal Condor conversion??? 😯
Cyg was IIRC getting 600fpe from a 3400psi fill (hope his bottle was rated for it)
I will only use 3,000psi as that is my tank rating.
Cheers,
Walter…
Also Cygnus used a 500grain slug to get 600fpe. I think he got around 580fpe with the 400grainers?
Man that thing had some serious muzzle flip!
What was Cygnus getting out of his 45cal Condor conversion??? 😯
Cyg was IIRC getting 600fpe from a 3400psi fill (hope his bottle was rated for it)
I will only use 3,000psi as that is my tank rating.
Cheers,
Walter…
Thanks Walter, that mirrors the calcs for determining the pressure behind a powder burner’s bullet; the smaller the diameter the less pressure on the back of the bullet…
What was Cygnus getting out of his 45cal Condor conversion??? 😯
I would venture a theory that a single pellet could go faster because the contact area with the groves and lands is reduced compared to multiple pellets…
Did you happen to notice any velocity changes when you ran the swaged .25 slugs over the multiple pellet approach?
Jerry, I officially recall my obnoxious idiot comment, you have been raised to good post and good humor status, my apologies… 😀
Does anyone know if the pressure from the tank is elevated when it is constricted into the tophat opening or does it remain constant at the tank pressure…?
3×14.3=42.9 grains for the .22
When I tested teh .25 I used 31 grain Kodiaks to determine where I wanted to go and settled on a 50 grain bullet. Since then I made teh 70 grainers to compare with Jerry’s 72 grain cast bullets.
pressure cannot elevate as it is what it is.
A constriction is a pressure drop across it so tank pressure is reduced along the path of restrictions by each pressure drop.
So in ‘our’ inline valves perhaps the tank has 3,000psi, the stem is at 2500psi and teh pellet sees 2000psi to start and perhaps finishs with 1000psi at the muzzle. Just WAG and no real way to measure those pressures esp at the speeds the pressure pulse occurs.
Walter….
Walter, how many pellets do you have to stack to get 42grains?? 😯
I would venture a theory that a single pellet could go faster because the contact area with the groves and lands is reduced compared to multiple pellets…
Did you happen to notice any velocity changes when you ran the swaged .25 slugs over the multiple pellet approach?
Jerry, I officially recall my obnoxious idiot comment, you have been raised to good post and good humor status, my apologies… 😀
Does anyone know if the pressure from the tank is elevated when it is constricted into the tophat opening or does it remain constant at the tank pressure…?
Thanks for the data. I appreciate the effort you went through to do the tests and post the results.
Given the power/velocity you generated by triple stacking pellets in your obviously hot .22, I’m a lot less skeptical of the 1100 FPS 40gr .22!
I don’t know just how much error is induced by using multiple rounds to get to a certain weight but I do know one airgun maker who has used the exact same process to check the power of a new gun when he didn’t have a slug of high enough weight available. Subsequent tests with a single slug gave results in line with the original multi-shot load…
BTW, I don’t think you’re an idiot. Since “it takes one to know one,” and since I’ve already been identified as an idiot…you must not be an idiot! Of course, one should never take the word of an idiot… 😀
Jerry, thank you. Same goes here…… I think…… 🙂
I have used this method for a couple years now, posted on the yellow and teh physics guy there thought it ‘most clever’ so I’m good with that!
I used multi loads to determine teh power capability of my .25 then swaged bullets to that weight with satisfyingly identical velocities.
1100 with a 40gr is now definitely possible and I must eat my words and scepticism humourously via my own gun!! now that is funny eh?
I’m going to check the condition of the orings and lube on my stem and breech and have another go here in a bit 🙂
Cheers,
Walter….
Walter,
Thanks for the data. I appreciate the effort you went through to do the tests and post the results.
Given the power/velocity you generated by triple stacking pellets in your obviously hot .22, I’m a lot less skeptical of the 1100 FPS 40gr .22!
I don’t know just how much error is induced by using multiple rounds to get to a certain weight but I do know one airgun maker who has used the exact same process to check the power of a new gun when he didn’t have a slug of high enough weight available. Subsequent tests with a single slug gave results in line with the original multi-shot load…
BTW, I don’t think you’re an idiot. Since “it takes one to know one,” and since I’ve already been identified as an idiot…you must not be an idiot! Of course, one should never take the word of an idiot… 😀
Well Tef as an example a 28 grain Eunjin goes the same velocity as 28.6 grains of 2×14.3 Crosmans. If anything the single pellet goes faster which I believe is due to the rear pellets wedging the skirts of the forward pellets.
Just think three pellets have six bearing bands where a single projectile may only have one and a bit more.
Physics is physics when it comes to horsepower 🙂
As Adam says ‘catch me if you can! ‘ teehee…..
Walter,
You have done it already and the others have a lot of catching up to do.
You are in the unique position of “Been There Done That”….LOL
Of course you know the locals are gathering the torches and coming after you…LOL
I’m not 100% convinced that shooting three pellets, adding the weight together and then checking out the velocity is a valid way to measure ft/lbs.
As stated in the post above the results:
using multiples of 14.3 grain Crosmans.
Allows the use of cheap pellets to determine power.
Walter….
I had read that earlier in the post, but I did not think we had idiots that would try it.
Sorry, do not mean to be rude, I’ll leave that to you.
Have a nice day.
Roy, you know something you’re not telling?
Now you got me wondering who the idiot is of whom you speak????
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Recall accepted, 😀
Here’s something to think about while Walter proves himself and me wrong with his own gun: A higher velocity might be reached with a tighter fitting slug.
Here’s the theory (first told to me by Barnes); if the slug holds its position for just a tiny time, the air pressure will build behind it so when it does slip its hold, there is more power available to accelerate it down the bore. A loose slug will move with the first rise in pressure and the bulk of the pulse will fill a larger volume.
If that sounds crazy, check out the NASA light gas gun details on Wikipedia. They actually use a 2mm thick stainless steel rupture disk to allow the pressure to grow before the projectile moves. When the pressure is high enough it blasts open the disk (the disk has been scored to open in a controlled manner and with minimum debris) and then sends the slug down the barrel at up to 7000 meters per second.
Jerry, I agree with this provided the friction is low on the trip out.
easily confirmed with my .25 as I can make tight bullets with straight walls and the identical weight in dual diameter. mmmmmmmm
Walter….