airsoft sites with vehicles and other unusual things
- Thread starter chris555
- Start date
jcheeseright
Supporters
- Jun 14, 2012
- 4,280
- 2,261
Yeah, the dot will be where it should be, the bullet isn't likely to go there though, unless it's a very short distance away.
jcheeseright
Supporters
- Jun 14, 2012
- 4,280
- 2,261
an aimpoint doesn't rely on refraction to work, it creates the illusion of a projected aiming point using a reflective piece of glass which is entirely self contained. where the dot points is where the bullet goes. If you're looking from water into air then yeah it'll be off, but then so are your eyes, so aiming becomes entirely moot!
NickM
Supporters
- Apr 29, 2012
- 560
- 181
Yeah but just like a straw in a drink "bending" the light from what you are looking at changes direction as it enters the mask then your eye, you get used to it but I doubt it would be good enough to take aimed shots at any kind of distance.
The bigger issue with it is the distance the projectile travels. The faster it is going the more resistance it will encounter, so it is doubtful anything fired from a standard firearm would travel more than a foot or 2. Try the Mythbusters video about swimming away from bullets, a 50cal only travelled through a few feet of water and was not lethal. In fact most of them the copper jacket peeled away from lead.
Also the percussive force on your ear drums would be immense and ear plugs would be pointless as the vibrations would travel through you. The vibrations from a blast underwater are especially important to understand. We had a section on my commercial diving course explaining the effects of blasts and percussion waves underwater on the human body. The wave travels through the tissues fine until it reaches a gas-water interface where it causes huge amounts of damage. See the link for a reported case.
http://www.wateroperations.com/sortie/issue2/article12.htm
Overall I'd say its a cool photo but would probably be unrealistic in the real world, although no reason they couldn't fire on the surface. Would be interesting to see someone try to aim and deal with the recoil on the surface.
The bigger issue with it is the distance the projectile travels. The faster it is going the more resistance it will encounter, so it is doubtful anything fired from a standard firearm would travel more than a foot or 2. Try the Mythbusters video about swimming away from bullets, a 50cal only travelled through a few feet of water and was not lethal. In fact most of them the copper jacket peeled away from lead.
Also the percussive force on your ear drums would be immense and ear plugs would be pointless as the vibrations would travel through you. The vibrations from a blast underwater are especially important to understand. We had a section on my commercial diving course explaining the effects of blasts and percussion waves underwater on the human body. The wave travels through the tissues fine until it reaches a gas-water interface where it causes huge amounts of damage. See the link for a reported case.
http://www.wateroperations.com/sortie/issue2/article12.htm
Overall I'd say its a cool photo but would probably be unrealistic in the real world, although no reason they couldn't fire on the surface. Would be interesting to see someone try to aim and deal with the recoil on the surface.
Baz JJ
Members
- May 23, 2013
- 2,349
- 502
Agreed. Real Aimpoint sights are waterproof down to about 80 feet and many assault rifles will fire under water - these look like G36 but I think the sighting and problems with percussion etc make it impractical, as you say.
Ive seen swimmers use floating drybags as supports for their rifles as they approach the target on the surface and assault troops on dry land.
Ive seen swimmers use floating drybags as supports for their rifles as they approach the target on the surface and assault troops on dry land.
Last edited by a moderator:
jcheeseright
Supporters
- Jun 14, 2012
- 4,280
- 2,261
firing a rifle or pistol underwater is no problem, all the percussive force gets sent down the barrel and away from you remember!
bullets underwater are every bit as lethal as normal, albeit with significantly reduced range;
http://www.youtube.com/watch?v=COea9JqJ7SM
there's a fine example of a guy who did a test firing at ballistic gel with a glock underwater, 5.56mm is a lot more hydrodynamic than 9mm and should have much better range.
bullets underwater are every bit as lethal as normal, albeit with significantly reduced range;
http://www.youtube.com/watch?v=COea9JqJ7SM
there's a fine example of a guy who did a test firing at ballistic gel with a glock underwater, 5.56mm is a lot more hydrodynamic than 9mm and should have much better range.
NickM
Supporters
- Apr 29, 2012
- 560
- 181
Significantly reduced range, http://www.youtube.com/watch?v=cp5gdUHFGIQ 2 mins in to avoid the camera setup explanation. 5-6 ft on an AK47/74? bullet. It seems to turn upwards in one of the shots and almost start tumbling.
Baz JJ
Members
- May 23, 2013
- 2,349
- 502
There are some great videos on this subject on You Tube.
The one with an AK firing while it is filmed by a high speed camera is interesting, The bullet goes about 6ft and then drops to the bottom. Yhe camera is running at about 18000 frames per second and shows the gas escaping from the blowback tube
ETA sorry crossed posts with Nick.
The one with an AK firing while it is filmed by a high speed camera is interesting, The bullet goes about 6ft and then drops to the bottom. Yhe camera is running at about 18000 frames per second and shows the gas escaping from the blowback tube
ETA sorry crossed posts with Nick.
Last edited by a moderator:
Ian_Gere
Retired Moderator
- Apr 1, 2012
- 6,417
- 2,050
Bear in mind that water doesn't compress, so it behaves very differently to air. I think it mainly comes down to the calibre and velocity rather than surface area and momentum. Simplistically, if a NATO 5.56mm hits water at 940m/s then ideally it takes approx 12.7 microseconds for the entire width of the calibre to pass the surface, which is handy for simple maths because the bullet is approx 12mm from tip to full width. However in reality we need calculus to mathematically examine what happens, but nonetheless we can say roughly that for the first microsecond all the bullet's force is applied to 1mm².
I'm a bit out of my depth here, but what I'm trying to get at is that all bullets which are pointed initially encounter the same width of column of water and that water has a fixed elastic constant which is very low, so there is only so much of it which can be shifted in a given amount of time, which means that there is a point at which it doesn't matter how much more force is applied to the water the tip of the bullet hits, kinetically the water cannot absorb it and neither can the bullet keep it as velocity so, according to Isaac Newton, that energy must be conserved in other forms - so, I think, that's why big heavy fast bullets get blown apart within a similar distance through water and period of time as smaller slower bullets.
I'm a bit out of my depth here, but what I'm trying to get at is that all bullets which are pointed initially encounter the same width of column of water and that water has a fixed elastic constant which is very low, so there is only so much of it which can be shifted in a given amount of time, which means that there is a point at which it doesn't matter how much more force is applied to the water the tip of the bullet hits, kinetically the water cannot absorb it and neither can the bullet keep it as velocity so, according to Isaac Newton, that energy must be conserved in other forms - so, I think, that's why big heavy fast bullets get blown apart within a similar distance through water and period of time as smaller slower bullets.
Baz JJ
Members
- May 23, 2013
- 2,349
- 502
Watching American Guns tonight on TV, the gunsmiths made a custom 50 cal sniper rifle with a carbon fibre barrel.
In the test shoot, they fired it a several hundred yards range and shot though about four or five fish tanks full of water.
The slug penetrated the tanks and entered a 50 gallon drum of fuel, igniting it.
I was more impressed by the Iowa x12 optics.
http://www.dailymotion.com/video/xshl9q_american-guns-season-2episode-7-tommy-gun-20-pound-50-cal_tv
At about 33 minutes
In the test shoot, they fired it a several hundred yards range and shot though about four or five fish tanks full of water.
The slug penetrated the tanks and entered a 50 gallon drum of fuel, igniting it.
I was more impressed by the Iowa x12 optics.
http://www.dailymotion.com/video/xshl9q_american-guns-season-2episode-7-tommy-gun-20-pound-50-cal_tv
At about 33 minutes
Last edited by a moderator:
NickM
Supporters
- Apr 29, 2012
- 560
- 181
What the actual F!!!!
What game do you stalk that requires a 50cal bullet to take down?!?
Anywhere else that conversation with a gunsmith would have gone something like this.
Uh yeah ... my ideal hunting gun is a carbon fibre 50cal, but its got to be under 20lb so can carry it easily.
What the f**k are you stalking, tanks or truck engines?
What game do you stalk that requires a 50cal bullet to take down?!?
Anywhere else that conversation with a gunsmith would have gone something like this.
Uh yeah ... my ideal hunting gun is a carbon fibre 50cal, but its got to be under 20lb so can carry it easily.
What the f**k are you stalking, tanks or truck engines?
Baz JJ
Members
- May 23, 2013
- 2,349
- 502
Similar threads
