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Posted: 12/26/2006 11:00:36 AM EDT
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How much water is needed for testing or expand/Frag The 223/5.56mm Wondering how many inches of water to stop a bullet! I would think it wouldnt be over 3 feet PLZ no need to Skool me about Gel testing 
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| If you know how far a bullet penetrates in gelatin/tissue, then you can estimate that bullets will penetrate 60-100% deeper in water. 3ft is more than enough, but 2ft is probably sufficient since most .223 bullets penetrate right at 12-14" in gelatin and tissue. |
Mythbusters did an episode on the discovery channel about this. Most high powered bullets fragmented upon impacting the water and lost all of their energy after only a few inches to a foot. |
Mythbusters even did an episode regarding firing guns underwater, ofcourse out came the garand again.... poor thing. As for shooting into water, Yeah, if you are shooting at close distances it's likely to put enough energy on a bullet to completely fragment it, no surprises there for everyone here who knows how 5.56 has a tendancy to fragment and to what ranges. But that velocity drops to the point where it won't fragment and watch how much water is needed for the bullet to come to a stop. Firing 22CB's into my backyard pool you'll see them go about 5-6 feet before they start to drop like a rock to the bottom. 300-400 yards out, I'd like to shoot a tank filled with water or atleast several 55galon drums lined up with my 50 to see how much it penetrated. It's a shitload of water and a rather unique thing to try and find a wide open area with the equipment to haul that much water out for a few shots. |
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Exactly - you gotta be real careful how much you take out of "mythbusters". Once the velocity slows, it can penetrate the water much further. Ammo types most be taken into cosideration. I have fired 9MM FMJ and after 2 ft the bullet exited the container with enough force to penetrate the plastic wall and keep right on trucking. The box o truth would give some decent information and he often used water as a stop. When I frag tested Wolf M193 - I had a solid 2 foot column of water, and that was enough to stop a fragmenting round, but would not have stopped it if it stayed intact. In any case - the hydraulic pressue was immense and detroyed the container. That is where your design work needs to focus. |
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When shooting the 5 gallon Buckets back in the late 80`s None of the Q3131 loads went threw the other side of the bucket I also used my Bolt Action 222rem with rem 50gr HP wich hit the bucket about the same as the M193 load We were just haveing fun! Wasnt trying to test anything We did also notice the there were alot of Splinters left behind on the 222rem50gr hp load as if might just try it out on the WOLF 75gr Except I wont shoot the Bucket 
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As a scientist, I have some serious problems with Myth Busters and their techniques. In Saving Private Ryan, the Germans were shooting into the water at moderate angles over relatively long distances; it seems that the 7.9mm bullet zooming out of the muzzle at around 755mps (around 2475fps) would have both slowed and started to droop by the time it got to the water line. This is very different from shooting into the water at close range, and the Myth Busters folks didn't even mention any ballistic issues like angle of impact interacting with speed at impact. I'd like to see controlled, carefully measured, REPEATABLE experiments done with REAL ammunition and REAL water over REAL ranges to see what's what. Sure, if you shoot DIRECTLY into water from a close range the bullet's shockwave is going to interact with the water and probably disintegrate the bullet within millimeters of water penetration. But once that bullet is stable and has slowed a bit, the shockwave isn't in the same spot on the bullet (any hypersonic shockwave moves backward on the moving body as the body slows, proportional to the body's Mach number-there's a really complex formula that works out to a Mach 3 body's leading edge shock wave moves back as the body slows so that when the body reaches Mach 2 the Mach 3 shockwave has moved into a wake position...). Get the bullet to just above another downward Mach transition, and the shockwave will be behind it. And remember, both the 7.9mm and .30-'06 were criticized for OVERPENETRATION at ranges of 600 yards/meters. That means that both had PLENTY of penetrating power at any practical range, and probably that, given the right circumstances, an MG42 COULD shoot INTO the water and cause casualties. Until someone does real experiments that can be repeated, we just won't know. And since it seems that Spielberg worked very hard at replicating what people who were really there saw and experienced, I'd say that Myth Busters got it wrong. |
Even provided you didn't have represenative ranges, downloading carefully you could get 100 yard velocities represenative of 500-600+ yards down range and conduct a bit more carefully designed testing. A chronograph and a good ballistics program helping to really explore things. Thing that would leave me most concerned is coming up with some kind of shoot tank that is big enough to contain the bullet as well as self seal should the bullet exit the side of the container, or keep it from exiting the top of the container if you're shooting through the front of it(bullets aren't always going to arc predictably as they tumble). After the "sniper versus sniper" episode I've been in contact with one of the folks involved with mythbusters, both by email and by phone, and have put that individual in contact with some other folks helping them build their rolodex of consultant types. Point blank, expect there to be a revisit on the sniper versus sniper issue. The person I was in contact with I spoke to them about the bullet into water myth and I'd be more than willing to invest time into a shoot if my schedule could coincide with the shoot(would gladly load up the 50BMG and haul it up there plus other chamberings and variety of ammo). |
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The angle that the round enters the water is VERY important. Since we all seem to have seen the Mythbusters show, remember that the first test was done shooting straight down into the water. I believe they found a 9mm round to be deadly at 7-8 feet. I don't recall them doing rifle rounds in the straight down test. They moved to a pool and an angle entrance for the rifle rounds. Also note, the 5.56 round will not fly nose first in anything that is more dense than air(so straight down test may not help this round). Unlike that 9mm round, the 5.56 will try to fly butt first. When it is sideways, this is when it fragments. The angled entrance into water will do this to most rounds. |
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Doubt very much that the angle of entry matters. Fackler's impacts with gel were 90 degree impacts, combine that with plenty of real world shoots at realistic ranges, and a wide variety of impact angles pan out to reveal similar results. Using the 5.56 as an example, most every modern spitzer tipped bullet has a center of gravity located rearwards towards the base of the bullet. Very simply put, they are gonna tumble very quickly upon entering a fluid/tissue medium. Fackler's studies found that the truely deep penetrators were things like the 6.5 Carcano and the 30/40 Krag, bullets with nose profiles very similar to that of African big game bullets and a nose profile that helps bring that center of gravity more forward(combine that with very long length in calibers to caliber ratios). The handgun rounds, look at a pulled bullet and the handgun rounds have a length to diameter ratio that gets really close to 1:1. And if it is a non-expanding round with thicker jacket, when it begins to tumble the amount of resistance it encounters is likely to be pretty proportional and not spike nearly as highly as with rifle rounds that when they tumble suddenly their length is bearing all that force along it's length. With those comparisons being made it only further shows the influence that the higher velocities have acting upon the rifle round. I've shot on water before and the only importance with angles come with respects to a ricochette when the angle of incidence grows small enough, done it with all kinds of calibers including 12gauge slug(fun watching them skip along the ocean 2-3 times before a final splay about 100 yards out). |
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An important thing to remember is that spitzer bullets do not stabilize until they are well away from the muzzle. That is why they will penetrate better as the range gets longer. I have personally seen a 7.62 NATO FMJ bullet fail to penetrate 12" of water, when fired from a distance of a few feet. That doesn't happen at longer ranges. It doesn't always happen at a few feet, but it did that time. The bullet did not fragment either, though it did bend, and a few grains of lead got squeezed out of the base. |
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Don't forget that much of the 7.9 ammo the Germans were using had steel cores (SmK, SmK L'spur and SmE types). I read a test report many years ago about the penetration of .50 BMG rounds in water. The navy wanted to see how lethal the .50 was in strafing attacks. All I remember was that the results were impressive. Something like 8-12' penetration. The Mythbusters did not come close to examining all the variables involved. Most military .50 ammo, especially the older stuff, has a steel core, even the ball rounds. Devil Dog |
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