It turns out an FMJ 5.56mm round travels four feet underwater before running out of steam.
How long before someone creates a underbarrel speargun?
[ Many thanks to jdun1911 for emailing me the link. ]
[ Video from MyGunExchange ]
There’s a speargun conversion for 10/22s that uses power-nailer blanks. And the crossbow upper for ARs.
0 
0David, thats is an awesome video. I just blogged it.
0 0Piston rifles can not defied the law of physic.
It doesn’t matter if it piston or DI. You’re not suppose to fire a rifle underwater because you know the water clog up the barrel. Objects that clog up the barrel is bad. Right?
I would like to know how he did this experiment and what ammo did he used.
0 0I’ve heard stories about this before but the physics part of me says you can’t fire a gun under water. Water doesn’t compress, at all. That having been established I would feel confident the barrel would rupture and the projectile would competely fragment without some type of modifictaion to the barrel that will allow the water to freely get out of the way. But even then, I can’t imagine a barrel surviving. I guess if you ported the barrel from the chamber forward it might not rupture, but even if it doesn’t what has been accomplished?
0 0I’m surprised it even cycled
0 0I think all that would accomplish is preventing the barrel from being ruptured? Other than that the projectile would probably still just go to pieces after leaving the air pocket, and, or, abruptly stop.
0 0http://www.outdoorlife.com/photos/gallery/survival/2010/03/surviving-undead-zombie-guns?photo=1
That’s what I was thinking of… don’t know how much better it would work underwater though.
0 0I would imagine if you put a very thin ballon type of insert into the barrel it would prevent the barrel from flooding with water. That should allow the projectile to make the trip down the barrel until impacting the water at the muzzle? Of course, the [projectile still isn’t going to be very effective after exiting the muzzle for more than a couplke of feet or so.
When seconds count, the police are only a few minutes away!
0 0Big Daddy,
I’ve seen it done with a standard gas tube. It sometimes work, and it sometimes blows the gas tube out.
0 0It seems like it’d be pretty easy to make a underwater shotgun shell.
Waterproof the primer until it’s hit, then use a compressed air cell to launch some flechettes.
Worst part would be getting water in the action, but you could allow for that with a purpose-built shotgun.
0 0They should try this using one of those 40gr Barnes Banded Solids.
0 0Assault rifle?
0 0Here you go 
http://world.guns.ru/assault/as69-e.htm
0 0sound is many times more powerful underwater than it is in air. How did they get away with that without going deaf
0 0I pretty sure that’s a piston rifle. As far as I know a DI one will not shoot underwater.
0 0Hmmm he sould try M-855 and see if they go loger out.
0 0Didn’t somebody have an underbarrel harpoon gun at SHOT or something lately?
0 0I’d heard of the Russian APS that wos mentioned, but hadn’t seen it before. There’s a video up on YouTube now, which also shows the 4 shot pistol they use:
http://www.youtube.com/watch?v=x-P578pnctU
Pretty cool I love the Engineering behind unusual guns, it’s one of the reasons I love this blog!
0 0Wouldn’t the water inside the length of the barrel, and the pressure of the bullet, cause the barrel to blow?
Somethings not right here.
0 0
I think all that would accomplish is preventing the barrel from being ruptured? Other than that the projectile would probably still just go to pieces after leaving the air pocket, and, or, abruptly stop.
http://www.outdoorlife.com/photos/gallery/survival/2010/03/surviving-undead-zombie-guns?photo=1
That’s what I was thinking of… don’t know how much better it would work underwater though.
I would imagine if you put a very thin ballon type of insert into the barrel it would prevent the barrel from flooding with water. That should allow the projectile to make the trip down the barrel until impacting the water at the muzzle? Of course, the [projectile still isn’t going to be very effective after exiting the muzzle for more than a couplke of feet or so.
When seconds count, the police are only a few minutes away!
I’m surprised it even cycled
I’ve heard stories about this before but the physics part of me says you can’t fire a gun under water. Water doesn’t compress, at all. That having been established I would feel confident the barrel would rupture and the projectile would competely fragment without some type of modifictaion to the barrel that will allow the water to freely get out of the way. But even then, I can’t imagine a barrel surviving. I guess if you ported the barrel from the chamber forward it might not rupture, but even if it doesn’t what has been accomplished?
There’s a speargun conversion for 10/22s that uses power-nailer blanks. And the crossbow upper for ARs.
David, thats is an awesome video. I just blogged it.
Piston rifles can not defied the law of physic.
It doesn’t matter if it piston or DI. You’re not suppose to fire a rifle underwater because you know the water clog up the barrel. Objects that clog up the barrel is bad. Right?
I would like to know how he did this experiment and what ammo did he used.
Big Daddy,
I’ve seen it done with a standard gas tube. It sometimes work, and it sometimes blows the gas tube out.
It seems like it’d be pretty easy to make a underwater shotgun shell.
Waterproof the primer until it’s hit, then use a compressed air cell to launch some flechettes.
Worst part would be getting water in the action, but you could allow for that with a purpose-built shotgun.
Hmmm he sould try M-855 and see if they go loger out.
Didn’t somebody have an underbarrel harpoon gun at SHOT or something lately?
I’d heard of the Russian APS that wos mentioned, but hadn’t seen it before. There’s a video up on YouTube now, which also shows the 4 shot pistol they use:
http://www.youtube.com/watch?v=x-P578pnctU
Pretty cool
I love the Engineering behind unusual guns, it’s one of the reasons I love this blog!
I pretty sure that’s a piston rifle. As far as I know a DI one will not shoot underwater.
sound is many times more powerful underwater than it is in air. How did they get away with that without going deaf
They should try this using one of those 40gr Barnes Banded Solids.
Assault rifle?
Here you go
http://world.guns.ru/assault/as69-e.htm
Wouldn’t the water inside the length of the barrel, and the pressure of the bullet, cause the barrel to blow?
Somethings not right here.