Shooting air rifle pellets with nail gun blanks
- Thread starter kodiakjack
- Start date
...And that's where the math scares me. I don't think I'll be trying this, at least not with yellow blanks.
Here's how the the logic breaks down: (correct me if you see a flaw in reasoning)
If a standard .22lr projectile has s muzzle energy of less than 125ftlbs, then this high speed pellet projectile (at 250ftlbs) has over 200% more energy.
Energy doesn't come from nowhere. It must be imparted to the projectile before it leaves the barrel. This is accomplished by a buildup of gas pressure in the barrel.
Therefore, there's a direct correlation between projectile energy, and barrel/chamber pressure.
So when firing these nail gun pellets, they're exposing their rifles to more than twice the barrel pressure that they were designed to reliably withstand.
Neat concept, but not something I'd be willing to try given that math.
duncansuds
CGN frequent flyer
- Location
- Weyburn, SK
lol, then the sig line under the cautionary explanation of why its a bad idea. Just find that funny, your likely right though.
elimsprint
CGN Ultra frequent flyer
- Location
- Kelowna, BC
Not to start an argument but it is 100% more energy not 200%. 2800fps is 200% of 1400fps but is in fact only 100% more than 1400fps as 1400fps is 100% to start with if you get what I mean. Also I have read that if you double the weight of a projectile at the same velocity you double the energy but if you double the speed of the original projectile you quadruple the energy so I don't really know if you are in fact doubling the pressure in the barrel to get double the speed/energy with a lighter projectile. Hopefully better minds than mine will do the math and chime in with the real answer.
K.E (foot/pounds) = mass (grains) X velocity (fps) X velocity ÷ 450,240
Since velocity is squared it has greater effect on energy...
BUT... energy is not the final word on penetration... momentum is also a factor, the formula for which is; mass X velocity. You will see that momentum places a greater (equal) value on weight... which is why when you apply equal force to the rear of a light projectile and a heavy projectile the heavy projectile penetrates deeper (depending on various factors and the medium)... as the heavy object resists changing direction or stopping to a greater degree.
elimsprint
CGN Ultra frequent flyer
- Location
- Kelowna, BC
Thanks for that but it still doesn't answer the pressure question. What is the formula to figure out the pressure needed to launch a 16gr projectile @ 2800fps compares to what is needed to launch a 40 gr @ 1200fps? My search-fu does not seem to be working today
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elimsprint
CGN Ultra frequent flyer
- Location
- Kelowna, BC
I found this, http://closefocusresearch.com/calculating-barrel-pressure-and-projectile-velocity-gun-systems and after downloading the spreadsheet I get the figures of 6490psi for the 40 gr .22LR @ 1200fps and a whopping 14,133psi for the 16gr pellet @2800fps I'm shocked, I find it hard to believe that it takes 2.177 times the pressure to drive something that weighs .4 times the weight of the other to a little over 2.171 times the energy since velocity has so much greater effect on energy than mass. No wonder I sucked at physics! I did run the 30gr hyper velocity and they have 10,352psi and 204 ft-lbs of energy so IMO the blanks firing the pellets would be safe in any modern .22 and I am going to give it a try Oh yeah, 17HMR which I believe are made on .22 actions has 19,931psi and 245 ft-lbs of energy so very close.
Oh yeah, 17HMR which I believe are made on .22 actions has 19,931psi and 245 ft-lbs of energy so very close.
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- Location
- Republic of Alberta
So cool lol
I found this, http://closefocusresearch.com/calculating-barrel-pressure-and-projectile-velocity-gun-systems and after downloading the spreadsheet I get the figures of 6490psi for the 40 gr .22LR @ 1200fps and a whopping 14,133psi for the 16gr pellet @2800fps I'm shocked, I find it hard to believe that it takes 2.177 times the pressure to drive something that weighs .4 times the weight of the other to a little over 2.171 times the energy since velocity has so much greater effect on energy than mass. No wonder I sucked at physics! I did run the 30gr hyper velocity and they have 10,352psi and 204 ft-lbs of energy so IMO the blanks firing the pellets would be safe in any modern .22 and I am going to give it a try
Cool. Thanks for digging that up. Confirms my earlier supposition that the increase in projectile energy shares the same ratio as the required barrel pressure.
elimsprint
CGN Ultra frequent flyer
- Location
- Kelowna, BC
You did notice that the 17 HMR has almost 6000psi more pressure than the pellet/blank loads out of the same, as far as I can tell, action as a .22LR so I think they should be perfectly safe to shoot. I have some yellows here, I just need some .22 pellets which I will get ASAP to try this out.
Hmmm. Not sure about the .17/.22 action, but the barrel diameters are different. If bored from the same size barrel, the .17 would have thicker barrel walls, thus being able to withstand higher pressures.
I'm sure most rifles could handle it no problem, but some .22s have frighteningly woosy-looking barrels like the savage rascal.
Well there's a good idea. Keep one "pellet load" in your pocket while out coyote hunting, so you can have something a little quieter for harvesting that squirrel or cottontail on your way to your stand.
I quoted it earlier with pellets from a Hornet... same applies to primer charged .223's... we are able to head shoot grouse and hares out to 40 yards. Your best bet for pellets is to use heavier (long) pellets, as they seat better in the neck and feed better into the bore... Beeman Silver Arrow pellets work good for us. We also FL sized the brass when priming, for better neck tension on the pellets.
