What a very strange question. You're describing explosions of
devices. The cartridge, the M-80. And you're describing associated
devices being damaged. The gun doesn't explode, it is damaged by
the 'exploding' cartridge. The mailbox doesn't explode.
The 'relief channel' is designed into the device, such as the gun,
But let mud get into the barrel, and watch the force get vented
otherwise. The door of the mailbox doesn't have to open. The box may
or may not be deformed/damaged by the M-80, with or without the door
opening. In fact, the box could be damaged by the localized
explosion, even with the door open.
I'll not tell you where I got my training with explosives, but I can
tell you
that they've been in business for a long time, and that their
training is frequently called upon to change someone's lifestyle.
I will again endorse the choice of using stump rotting chemicals, and
ignoring you.

SteveB wrote in message
news:rastb.14271$Q64.1419@fed1read03...
As in when a cartridge in a gun is supposed to fire, and the "cork"
(lead) pop out through the barrel, but doesn't and causes the gun
to "explode"?

As when a blackpowder M-80 is put into a mailbox, and the door
doesn't
"pop"
open to relieve the pressure, but the mailbox is destroyed?

Things explode all the time although they have a relief channel.

Where did you go to explosives school? I think you should ask for
a
refund.
What state do you live in? (other than the state of confusion) I
want to avoid that state in my travels.

Steve


As I said in an earlier post, true explosives do not need any
confining at all to do their damage. Think about it. Does a stick of
TNT need confining to explode? No. Will it do damage if just laying on
the ground? Yes. You can enhance the damage by tamping it into the
blast hole, but it is not necessary. C4 explosive needs no confining
and can be molded to whatever suface you wish to destroy. It can be
shaped to do more damage. If you had a flat piece of C4 and scooped
out a depression in it, oddly enough that depression is where the most
damage will be done. Smokeless powder that is used in modern firearms
is NOT an explosive. If you burn small arms ammunition the majority
of the cartridges will not detonate, they will rupture relatively
harmlessly and burn.

ANFO is also a true explosive that needs no confining. And it is
perfectly legal to buy the components, just like blackpowder and
smokeless powder, and perfectly legal to use any of theses for their
intended purposes, but it is absolutely not legal to use any of them
to make an explosive device.

Have fun

Firearm misfires will readily breech carbon steel and blow your face off.
It happens. Gunpowder is explosive under pressure.