Shooting through an aquarium

[reynolds357]

Tonight on Mythbusters, they tried to shoot through a 30 gal aquarium into a test dummy using a 12ga. shotgun. They fired Bird shot, Buck shot, and Slug. Amazingly, none of the rounds struck the test dummy. The buck did not even break the back glass of the aquarium. The concussion wave of the bird shot broke the back glass, but the shot did not exit. The slug broke the back glass but fell on the ground in front of the dummy.
Said all that to say this, I wonder how large a centerfire rifle cartridge it would take to kill the dummy behind the aquarium? For simplicity of discussion, bullet used can be FMJ or TMJ.

 

[jmr40]

They did a similar test in a swimming pool with rifle rounds a few years back. I don't remember the details, but none would have done much damage to a human more than about 3' below the surface. They included the 50 BMG IIRC. I could be wrong, but the slower handgun rounds actually did better than rifle rounds if I remember correctly. But even then not by much.

 

[chris in va]

I saw that a while back too. It seemed to depend on the angle as well, and all rifle bullets disintegrated within 2-3' of the surface.

I do seem to remember them firing a FMJ 9mm straight down into a vertical cylinder tank and it blew out the bottom.

 

[bamaranger]

UDT

I read a book on the frogmen of WWII some many years ago, and one of the things I recall clearly was the commentary of being able to catch spent small arm slugs underwater with their hands while swimming not just all that deep at all.

 

[briandg]

Subsonic rounds with high sectional density, small meplat with sharp carbide needle sharp penetrator.no spec Oog all ogive or boat tails

300 Mac, 220 grain, subsonic round, ...straight dowel shaped bullet with sharp, h hard tip that hill break the glass.

Solid copper or bronze, lead or jacketed lead, please stay home.

 

[briandg]

Here we go, I may have an answer.

Submarine ballistic missiles are not rocket shaped, they are clean and simple cylinders with domed cap. They are deployed from underwater. Iirc, the launch sequence is a charge of air ejects the missile. Firing the solid fuel motors within the bays or within the water nearby woul badly damage the sub. The rockets deploy as the missile leaves the water. Missiles can be launched from 100 feet or more below the surface, iirc.
.375 300
This woodleigh .375-300 grain bullet is built to penetrate deeply and straight, and would blow through water better than most. It is practically identical to a sub missile.

Photo courtesy of midway usa
http://www.midwayusa.com/s?targetLo...&Ns=p_metric_sales_velocity%7C1&Ntpc=1&Ntpr=1

 

[1100 tac]

Let us know how your side by side comparison works out.

 

[briandg]

let me crowd fund this. A safari grade rifle, a few hundred rounds of ammo, and I could bust mythbususters.

 

[taylorce1]

Mythbusters found bullets fired at close to subsonic speeds penetrated water better.

Hiding underwater can stop bullets from hitting you.

partly confirmed

All supersonic bullets (up to .50-caliber) disintegrated in less than 3 feet (90 cm) of water, but slower velocity bullets, like pistol rounds, need up to 8 feet (2.4 metres) of water to slow to non-lethal speeds. Shotgun slugs require even more depth (the exact depth couldn’t be determined because their one test broke the rig). However, as most water-bound shots are fired from an angle, less actual depth is needed to create the necessary separation.

 

[reynolds357]

They used a 12ga shotgun slug in this test. It did the best, but still did not hit Buster.

 

[Mobuck]

From my personal testing, I'd say a subsonic from the 300AAC would make for a perforated "Buster". I've seen a 208 A-Max penetrate 4'(in basically straight line) of water filled milk jugs and continue on to be lost in the back stop. I doubt 2' of water in an aquarium would stop or deflect it.
The "myth busters" staff aren't(weren't since it's gone now) really knowledgeable about bullet design(counter to the frequently commented on expertise) and often choose bullets, ammo, or cartridges which are not optimum for the purpose.

 

[MJFlores]

I saw a similar thing recently, in a video where a guy in a pool remotely fires I think an AR at himself underwater. I was surprised, he seemed surprised too...the bullet only went I think 8 feet or so under water before dropping to the bottom of the pool. I was surprised at the outcome.

 

[Magnum Wheel Man]

Ok... captain obvious here... The aquarium is only good for cover, for one shot a 2nd shot fired a few seconds later would be a kill shot

 

[briandg]

The 300 aac would be very good. Supersonic creates a disturbance going through air, through water, which has so much more mass and inertia will drag that energy down incredibly. High sectional density concentrates every scrap of the power on a small point. If you used a bullet that had a profile like the standard .223 I wonder if you would get yaw.

A 38 special with semi wad cutters would probably do a whole lot better than a sub fmj 147 9mm.

If you see a test tank at a ballistic lab they aren't built very large

 

[FrankenMauser]

At supersonic velocities, it's all about nose cavitation to prevent the bullet from disintegrating, and keeping the center of pressure on the base of the bullet so it doesn't tumble.

The Russians did it with one of their underwater assault rifle loads.

Woodleigh does it with their "hydrostatically stabilized" bullets.

Mt. Sourdough (a MarlinOwners forum member) did it with reduced velocity and my design intended to avoid nose-shearing in tough game animals, with harder lead alloys:
FrankenMauser water test - 11 feet of penetration. (Video and testing by Mt. Sourdough.)
That bullet is a beast.

At higher velocity, the bullet repeatedly veered wildly after about 16 jugs (5.75" square), so full penetration couldn't be measured. Nor could the bullet be recovered; but there were no apparent fragments left behind.



When you compare water jug testing to water tank testing, penetration is reduced in actual tanks, since the hydraulic forces are more constant. But jugs are the easiest thing for most of us to use...

 

[Magnum Wheel Man]

I actually wonder if there are differences in results between the aquarium, & a swimming pool... the aquarium has the 1st layer of tempered glass, ( which shatters as soon as it gets hit ) which then puts all the contents in motion, the oposite direction the bullet is trying to go ( forcing it to swim upstream ) ... I'd suspect actual penitration would be less through an aquarium, than in a pool, because of the glass, & the engergy of the moving water... where as the pool is static

 

[briandg]

Franken mauser, brilliant. I wish you had shown the bullet and describe the velocity. I'm interested. A lot of t cast bullet designs would do well in this test. I've known all along that jugs at intervals would be very different than a solid wall of. Water. The impact woul create a cavity that wouldn't perform like a solid mass of water.

 

[TXAZ]

If I had to shoot through a 30 (or 60 /100) gallon fish tank to a target on the other side, the simple technique of firing 2 shots, separated by 1/2 to 2 seconds would provide a much simpler solution.

 

[kilimanjaro]

So apparently shooting fish in a barrel isn't easy after all.

Alas, another myth busted. Civilization falls away, the center cannot hold.

 

[JimPage]

Water resistance isn't the only thing to worry about shooting at water. Light bends with water. You have to aim below what you see underwater at any angle less than Straight down.