Wreck Ammo Dangerous ?

With wrecks for diving becoming more and more accessible, I am a little concerned about the World War II wrecks which still contain "unused" ammunition. How safe is it if a diver shifts or moves any of this stuff ? I met a diver once who claimed she had once recovered "live" ammo form a World War II wreck including 50 calibre and antiaircraft ammunition. She claimed she was living proof that it was perfectly safe to do so. She argued that this type of ammunition is designed to be safe to handle, transport and store for long periods in a wide range of climates and conditions. She thus claimed it was perfectly safe to accidently bump it or even remove. However, others have claimed that World War II era ammunition on a wreck is very unstable, as it has been exposed to seawater and pressure for, in some cases, more than sixty years. Some liken it to nitroglycerine - don't even disturb it or it could explode ! What is the straight goods on this stuff ? Except for in the movies, I have never seen this stuff above water let alone underwater. But I would like to know the risks I am facing if I ever do come across it.
Thanks.

Explosives can become highly unstable and dangerous over time. For this reason the general rule is to leave any explosive alone, assume it's unstable.
However, most explosives also deteriorate to harmless over time in salt water, so the probability that you're dealing with an unstable explosive is remote.
Basically, you just gotta ask yourself one question... "Do I feel Lucky?"
Well do ya?
Rick
(I leave it alone)

Originally posted by Rick Murchison
Explosives can become highly unstable and dangerous over time. For this reason the general rule is to leave any explosive alone, assume it's unstable.
However, most explosives also deteriorate to harmless over time in salt water, so the probability that you're dealing with an unstable explosive is remote.
Basically, you just gotta ask yourself one question... "Do I feel Lucky?"
Well do ya?
Rick
(I leave it alone)

Click to expand...

Well you beat me to it, your thoughts about cover it. I've seen a few programs about diving in the South Pacific where many of the war wrecks do have live ammo -- each one of them has warned diver that the ammo is unstable and not to move/take it.

I remember back in the early 1990's a WWII anti-ship mine washed ashore in West Australia - the classic spiky ball type you see in all of the movies. This thing had been in the water for close to 50 years, and eventually was washed ashore during a storm. Presumably it had been lying on the bottom just offshore for most of that time. Anyway, either the navy or army came along and blew it up, and it gouged a 12 foot deep crater in the rocks it was on.

Tried to find a reference to it on the web, but no luck

I'd leave anything I found underwater alone.

Having been an ordnance technician in the Navy, I can say that YES, that old stuff can be very nasty.
There's one type of explosive commonly used that becomes highly unstable after having been submerged in saltwater & then dried out.

We used to dispose of the outdated stuff by loading an old Liberty Ship full of the junk & taking it out and scuttling it. A half dozen depth charges were included in the batch, set to go off at 600'. Seismographs would pick up the resulting thump.

Gee that would look fantastic on video if you sent down a submersible with a camera alongside of it when she went off...

TNT, the common HE compound used in WWII by all sides in their munitions is perfectly stable when saturated with seawater. (Or at least as stable as it ever gets.) It does have a property that tells you to leave it in seawater though.

When seawater saturated TNT dries out and and the salt precipitates out in the explosive matrix it "preloads" the charge such that minor shock can set it off even without any fusing mechanism in place.

ANYTHING that could have an internal explosive charge found on the bottom should be left there! Priming and Fuzing compounds may or may not be damaged by seawater flooding, but the fuzing mechanism WILL be. Some "inertial" fuzing mechanisms will "fail to fire" if specific parts corrode away and the warhead is even slightly jarred. The only exceptions to this rule are munitions "working their way to the beach" that could be found by youngsters and accidentaly detonated by them. If TNT containing munitions are removed keep them WET and well cushioned (preferably suspended in mid water collumn or merely marked and left on the bottom) while calling the local EOD guys to come deal with it.

Small arms powder is not destabilized, however tracer and incindiary rounds will remain active even after saturation. "Pulling" projectiles to "remove the powder" can lead to really bad things happening if the round was a tracer or incindiary. Normally one in 5 or 10 of belt fed munitions will be tracer or incindiary. Lead based priming compounds and mercury fuliminate priming compound are not significantly harmed by seawater flooding and CAN be right touchy once dried out.

FT

that would look fantastic on video if you sent down a submersible with a camera alongside of it

Click to expand...

I'd estimate that the blast of one of those ships going off would have a 100% kill radius of at least a quarter mile.:boom:

"alongside" might have been a poor choice of words :boom:

On a similar note to the original topic, I regularly found .303 ammunition dated from the late 1930's and early 1940's as a child, when I accompanied my father to the local rifle range where he was a member. The range was a former army range, and was used for training prior to and during WWII. This was in 1980-1984, so the stuff was 45 years old or so, and had been laying around in paddocks for all of that time, totally exposed to the elements. I remember someone throwing one in a fire after a few too many drinks at a post-match barbeque - needless to say it pretty much exploded. The old cordite inside still packed a punch - the last we saw of the case was a red blur flying off into the distance like a tracer shot... I found the projectile nearby, which had part of the neck of the case still attached. With no breech to contain the pressure generated by the cordite igniting, the whole thing had just ruptured rather dramatically. Luckily no-one lost a finger or eye.