Tunnel range and change of POI

[ED3]

Is your tube/tunnel sufficiently ventilated? It would seem that if it wasn't, that you would have considerably more pressure at the end of the tunnel than at your end. By shooting you would be forcing air toward the target end of the tunnel, if there is no where for the air to go vent pressure would go way up. I would also think this would not be consistent with different calibers and that your variations would not be uniform. It may not be uniform, but very minor and therefore appear uniform. If this is actually happening, a larger tube/tunnel and better ventilation, exhaust fan or vent double the size of the end vent, might change the effect. I also could have it totally backward, in that you actually have an velocity advantage with the tube. A 2 foot diameter tube is very small and could act like a suppressor too allowing the bullet to run faster. You can pick up 20fps running a suppressor at my altitude. Pure speculation on my part, but it is an interesting thread and fun to postulate.

I am not a physicist or astrophysicist for sure. I also think I could have it totally backwards because you in the southern hemisphere.​

Supersonic bullets travel faster than the resulting pressure wave, which travels at the speed of sound.

Mechanically moving air through the tube/ tunnel would defeat the purpose of the tube/ tunnel, which is dead calm air.

 

[Sniper338]

my .02 cents

I think yall got too much dam* time and money on your hands to build an underground tunnel.

if you shoot .2s and .3s in a tunnel that makes it a total waste because many of us can shoot .0s and .1s at 100 yards in no tunnel at all WITH a wind..


just to stir the shi* pot... lol

 

[Delfuego]

Supersonic bullets travel faster than the resulting pressure wave, which travels at the speed of sound.

Soundwaves travel at the speed of sound. Shockwaves can travel faster. There is a shockwave in front of the bullet. Pressure is also still pressure, it has to go somewhere. That is why air flows out the shooter end of the tube.

I also postulated that it may be acting as a quasi suppressor and allowing the bullet to travel faster than under normal conditions.

No perceptible wind influence and "Dead Calm" are different also. In reality dead calm air doesn't really exist. The effect would be negligible or unmeasurable but not missing.