Can underwater ammo explode?

[lowviz]

I was diving the Morgan out of VB years ago and surfaced at the ladder right in the middle of 2 guys trying to whack the projectile out of the top of a 75mm shell they had brought up ...//...

I couldn't care less about wet or dry powder. The problem is with the detonators and, quite often, there are TWO of them. The one that ignites the propellant is obvious, but the uninformed often ignore an even larger threat:

Chapter 13 WARHEADS

To answer the OP's question, "Most definitely, YES!"

 

[Vicko]

On and around the plane wrecks here you can find literal tons of 50 cal incendiary ammo, there's so much of it that as kids we could find it at beaches. If you remove the bullet and tap the powder and the blue stuff out it still burns. And apparently what we as kids did not know if you hit it hard enough it detonates... So that's stil live, even unstable ammo just sitting there underwater since 1944.

 

[AfterDark]

On and around the plane wrecks here you can find literal tons of 50 cal incendiary ammo, there's so much of it that as kids we could find it at beaches. If you remove the bullet and tap the powder and the blue stuff out it still burns. And apparently what we as kids did not know if you hit it hard enough it detonates... So that's stil live, even unstable ammo just sitting there underwater since 1944.

With the 40MM ammo I found I would use 2 small chain wrenches, one on the case the other on the projectile then turn them in opposite directions back and forth pulling on the wrench around the projectile slightly until the projectile was removed.

When I would find loading practice rounds with holes drilled thru the shells I use heat around the case neck to make protectible removal easier. Those had no primer or powder and were marked on the case head as "for training" nice looking paperweights if the bullet was left in it.

 

[AfterDark]

I couldn't care less about wet or dry powder. The problem is with the detonators and, quite often, there are TWO of them. The one that ignites the propellant is obvious, but the uninformed often ignore an even larger threat:

Chapter 13 WARHEADS

To answer the OP's question, "Most definitely, YES!"

Those are not small arms ammo. Those come more under that which should be left alone as I mentioned in an earlier post like a torpedo or depth charges.

Wet powder does not ignite. Wet primers however I don't know. I've always been very careful with the primer ends of the 40MM's I've handled. I may take a primed pistol case and fill it with water, let it sit for a week then empty it, stick it my revolver and try to fire off the primer. I know #11 percussion caps work when wet so I expect primers might too, however primers are sealed in a case, #11 percussion caps are handled by the user and are expected to be exposed to the air and rain so maybe made differently.

Although 40MM are not considered small arms either they are constructed like small arms ammo in that the components are the same: case, powder, bullet and primer and are assembled and work the same. Also I have only found what looks to be AP and training rounds. I have yet to encounter flak type rounds that contain explosives of their own as well shrapnel. Those I would also leave to mother nature.

 

[OceanEyes]

To the OP.

Can it ignite, detonate, explode, or fizzle? Yes.

Will it? That depends on the specific nature of the materials and the circumstances of their treatment. Unless you know precisely what you are looking at, and are certain that you know exactly how to treat it, you’re probably best advised to leave it alone.

 

[driftwood]

This was twenty years ago when I was working at a military museum. We had an elderly lady walk into the offices with a bag of WWII 20mm rounds her late husband brought back from the navy after his discharge. Thanked her very much and told her we would take care of it for her.

Gingerly picked the bag up and walked it back to the vault where we stored all of our Class II materials/artifacts. Next move was to call EOD and let them "process" the rounds.

Personally, I don't aspire to receive a Darwin Award.

 

[Celt]

I have yet to encounter flak type rounds that contain explosives of their own as well shrapnel. Those I would also leave to mother nature.

You need to be careful with the Mercury(II) fulminate in the caps of any percussion rounds but any flak heads I’ve come across are not armed until they’re fired.

 

[Celt]

Base of a flak head, when fired the copper disc on the base is driven forward and the detonator is armed

 

[AfterDark]

You need to be careful with the Mercury(II) fulminate in the caps of any percussion rounds but any flak heads I’ve come across are not armed until they’re fired.

That's good to know thanks! The rounds I've found had all leaked and were filled with water. I suspect the mercury had been leached away after 70+ underwater.

 

[LCoolio]

Linked is some Navy divers handing and destroying some UXOs on the East Coast of Canada.

Bell Island's got an explosive problem — and these military divers are back to defuse it