What am I missing?

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Broken_WV_Guy

Broken_WV_Guy

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Dec 11, 2019
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West Virginia, United States
I'm new to the world of PCP and my mind is blown to all the possibilities out there. While watching every youtube review I can find, I can't help but wonder why someone isn't building a PCP gun to shoot .17HMR bullets at around 2800 ft/s or wherever is most ideal. If companies can build a .50 cal with 700ft-lbs of energy then the power should be there.

Pellets are great and I've been amazed at how accurate they are since shooting 3 position in High School JROTC, but obviously aren't as good as a bullet for range and accuracy.

What am I missing? Why hasn't someone done this or something similar yet?
 
If it can be done wouldnt you think they would of made it? Dont compare airguns to firearms. The transfer port hole on a .177 is very small. There is a limit on how much air can pass through it from the valve to the barrel. Big bore airgun have a larger transfer port, so more air can go through pushing larger slugs.
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Why not just use a larger transfer port on a smaller caliber tho?
 
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The closest is the HMAir17 by tofazfou. Look him up on YouTube. It is a custom and not a factory gun though.
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Thanks, that's cool but not exactly what I was thinking. He designed a slug the same shape as the .17HMR. Cool, but I'm talking about using air to propel a rifle cartridge at a similar speed as a rifle would.

Nobody really tries to get more FPS out of a .177 pellet because it's not going to be stable. Ignoring that fact, how fast could you get a .177 pellet going with today's technology? I would think it would have to be at least getting close with the power figures I've seen.
 
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Larger bullets/pellets have the physical benefit of better Ballistic coefficient. Small projectiles do not hold velocity and are worse for wind drift.
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I'm comparing a small bullet to a large pellet/slug. I'm not sure but wouldn't a .17HMR have less wind drift than a .50 cal slug?
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I'm not sure how that applies. That pressure is needed to contain the chemical reaction. I'm talking about using air.

The barrel length needed might be too long and make it pointless. What about using some kind of wad to utilize a larger barrel for more air volume tho?

I'm simply amazed at the technology today compared to 1995 when I shot competitive pellet. Sure the smaller calibers are pretty much the same but I never thought there could be a .50 cal pellet rifle that could kill a bear. Just makes me wonder what else could be possible if that much power is able to be produced with just air.




 
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Most airgun air containers are limited to 4500 psi, I am not aware of a higher fill pressure. Commercial tanks can be filled to 6000 psi for welding gasses, but that is not currently available in a portable format. 6000 psi Nitrogen tanks are heavy bastards, and still less than 1/4 the psi of a 17hmr.

24000 psi contained by the chamber of a 17hmr gun means that there is 24000psi pushing on the .17 bullet. About 5x the pressure available from atmospheric gas compressed in a PCP gun. Good luck chasing your dreams. Wake me up when you find a way to magnify the power of PCP 500%.
 
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If it can be done wouldnt you think they would of made it? Dont compare airguns to firearms. The transfer port hole on a .177 is very small. There is a limit on how much air can pass through it from the valve to the barrel. Big bore airgun have a larger transfer port, so more air can go through pushing larger slugs.
Click to expand...



Why not just use a larger transfer port on a smaller caliber tho?
Click to expand...

You really dont get how airgun works huh? The transfer port can not be larger than the pellet or slug. When you chamber them, they will fall into the transfer port if it is larger than the pellet or slug. Even if you find a way to fill your gun to 1000000 psi. You can not push all the air into the tiny .177 size transfer port hole. It will either blow up or the air wont pass through the hole quickly enough before the valve closes. Firearm do not use a transfer port. When the powder burns it create pressure behind the bullet and pushes it. With airgun, the air must past through the transfer port before it can get into the barrel. 
 
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Most airgun air containers are limited to 4500 psi, I am not aware of a higher fill pressure. Commercial tanks can be filled to 6000 psi for welding gasses, but that is not currently available in a portable format. 6000 psi Nitrogen tanks are heavy bastards, and still less than 1/4 the psi of a 17hmr.

24000 psi contained by the chamber of a 17hmr gun means that there is 24000psi pushing on the .17 bullet. About 5x the pressure available from atmospheric gas compressed in a PCP gun. Good luck chasing your dreams. Wake me up when you find a way to magnify the power of PCP 500%.
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I still don't think you would need anywhere near that PSI to reach the 2800 ft/s. I saw a few guns with titanium canisters with a 5000 psi fill. Not sure how you would fill it but they exist. Different gasses could be used, but air would obviously be ideal.

https://hardairmagazine.com/ham-columns/how-to-obtain-the-maximum-power-from-a-pcp-air-rifle/ (hope this link is ok) I just found this but i'm not 100% on the math. The area of a .17 is what makes it the most difficult but thats where a wad could help, right?

I'm not saying this would be a replacement for a pellet gun. Just wondering if it's possible.
 
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If it can be done wouldnt you think they would of made it? Dont compare airguns to firearms. The transfer port hole on a .177 is very small. There is a limit on how much air can pass through it from the valve to the barrel. Big bore airgun have a larger transfer port, so more air can go through pushing larger slugs.
Click to expand...



Why not just use a larger transfer port on a smaller caliber tho?
Click to expand...

You really dont get how airgun works huh? The transfer port can not be larger than the pellet or slug. When you chamber them, they will fall into the transfer port if it is larger than the pellet or slug. Even if you find a way to fill your gun to 1000000 psi. You can not push all the air into the tiny .177 size transfer port hole. It will either blow up or the air wont pass through the hole quickly enough before the valve closes. Firearm do not use a transfer port. When the powder burns it create pressure behind the bullet and pushes it. With airgun, the air must past through the transfer port before it can get into the barrel.
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I meant use a larger transfer port than a standard .177 along with a wad or sabot.
 
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The 50 cal air rifle gets it's energy rating in FPE primarily from the massive weight of the projectile, the velocity is relatively slow, usually sub 1000 fps.

Currently the best airguns aren't anywhere near as accurate as firearms. One example is a .282" 5 shot group benchrest record at 600 yards with a 6mmBRA. Aggs at 100Y with 6mmPPC's can be in the .1's for an entire weekend with many groups in the 0's. This and many other reasons are why we look at firearms and airguns differently and use them for separate reasons.

One reason for sure is the glaring impracticality of attempting 17hmr speeds with air. Not sure even NASA can do it with their $27 billion budget???




 
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The 50 cal air rifle gets it's energy rating in FPE primarily from the massive weight of the projectile, the velocity is relatively slow, usually sub 1000 fps.

Currently the best airguns aren't anywhere near as accurate as firearms. One example is a .282" 5 shot group benchrest record at 600 yards with a 6mmBRA. Aggs at 100Y with 6mmPPC's can be in the .1's for an entire weekend with many groups in the 0's. This and many other reasons are why we look at firearms and airguns differently and use them for separate reasons.

One reason for sure is the glaring impracticality of attempting 17hmr speeds with air. Not sure even NASA can do it with their $27 billion budget???



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What would happen if you shot a .17HMR inside a .50 cal sabot? You wouldn't need near the psi due to the light weight of the projectile and we haven't even talked about ultra light weight projectiles either. I know accuracy would be a big issue but that's just a gross exaggeration of what I am thinking.

I wish I had enough knowledge and confidence to do the math. It might not get to 2800 ft/s but could it get going fast enough to stabilize the round?
 
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Check this out

https://www.gatewaytoairguns.org/GTA/index.php?topic=106617.0
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Thanks for that Dairyboy. Very informative and he was using a pellet. Imagine a better shaped projectile.



Thanks for the encouragement fuznut. Small minded people tend to think everything they don't know is impossible. The more I learn the more I realize how dumb I am.



Low and behold, someone on the track already back in 2013. https://www.youtube.com/watch?v=kZP6pE5x8-4



I'm sure glad I don't know everything.
 
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Early 80’s



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