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Old 2018-05-23, 15:23   #452
kriesel
 
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Quote:
Originally Posted by science_man_88 View Post
The problem then is the rock won't knock down a 750 grain bullet at 2252 fps
Yikes, 750 grains, that's just over 1.7 ounces, sounds like a 50BMG, and indicated velocity implies at range >500 yards. That's a rather rare and expensive arm, also expensive to operate at $3.50/round in bulk. Cumbersome at 23 pounds and 48 inches. School mass shooters tend to be not only murderous and mad and cowardly, but also pathetic losers who can't possibly afford a $10,000 luxury weapon.

The reason AR-15's are popular with that pathological group may be because they're inexpensive. It's not that they're lethal; they and their little ~55-grain projectiles are marginal or below minimum requirements (regulations) for deer hunting, more appropriate for coyote sized game. Typical projectiles for deer are ~165 grain (AR-10 or similar).
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Old 2018-05-24, 00:25   #453
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Originally Posted by kriesel View Post
The reason AR-15's are popular with that pathological group may be because they're inexpensive.
And they are everywhere.

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Old 2018-05-25, 17:39   #454
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What bothers me is the sheer number of idiots who get a cactus needle in their butt and think it is an excuse to shoot a bunch of people. Are we becoming more insane?
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Old 2018-05-25, 17:40   #455
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Originally Posted by Fusion_power View Post
Are we becoming more insane?
It sure looks that way.
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Old 2018-05-25, 19:06   #456
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Default The insanity continues ...

Who'd thunk that using a oven would be the best place to store your gun and ammunition.

http://www.vindy.com/news/2018/may/2...s-oven-did-it/

http://www.tampabay.com/news/publics...plodes/1275754

Good plan guys. Keep up the good work.

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Old 2018-05-25, 23:07   #457
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Quote:
Originally Posted by retina View Post
Who'd thunk that using a oven would be the best place to store your gun and ammunition.

http://www.vindy.com/news/2018/may/2...s-oven-did-it/

http://www.tampabay.com/news/publics...plodes/1275754

Good plan guys. Keep up the good work.

Multiple technical issues in those articles. Modern ammunition is an assembly of case, primer, propellant, and bulllet. Bullets don't explode, they fragment on impact, being made typically of inert metal. What happens I think is the primer is set off by differential thermal expansion, igniting the propellant, and bursting the (usually brass) cartridge case if it's in a magazine or loose rather than in a firearm's chamber that's designed to contain the tens of thousands of pounds of pressure produced. (Brass expands thermally more than steel. Or maybe the primer or propellant just becomes unstable from the heat.)

One such incident occurred in the oven of a former Madison WI chief of police. He was in the habit of putting his service weapon a different place in his residence each day upon return home. That evening he chose the oven. Later he got hungry and started the oven on preheat and somewhat later got reminded of his weapon's location when one round went off. The policy about reporting every round discharged was followed, so the city council was notified, and the media got hold of it too.
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Old 2018-05-26, 02:25   #458
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I would bet on the heat setting off the primer. The primer has to be more sensitive than the propellant. It is normally set off by percussion energy, but enough heat should do the trick, too.
@Madison police chief, 'accidentally' toasting his weapon. It is no accident with someone that dense.

Last fiddled with by kladner on 2018-05-26 at 03:21 Reason: the
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Old 2018-05-26, 15:28   #459
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Originally Posted by kladner View Post
I would bet on the heat setting off the primer. The primer has to be more sensitive than the propellant. It is normally set off by percussion energy, but enough heat should do the trick, too.
@Madison police chief, 'accidentally' toasting his weapon. It is no accident with someone that dense.
Re primers, I had thought so too. But https://en.wikipedia.org/wiki/Cooking_off seems to say otherwise. (What better place to "cook off" a round than an oven?)

Re the Madison police chief, that was a couple of chiefs ago, and has not reoccurred. UW-Madison hasn't taken any chances though, and followed one female chief of ~26 years tenure with another (with zero cook-offs).

Holy exploding billiard balls: https://en.wikipedia.org/wiki/Nitrocellulose#Other_uses
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Old 2018-05-26, 16:46   #460
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Quote:
Originally Posted by kriesel View Post
Re primers, I had thought so too. But https://en.wikipedia.org/wiki/Cooking_off seems to say otherwise. (What better place to "cook off" a round than an oven?)

Re the Madison police chief, that was a couple of chiefs ago, and has not reoccurred. UW-Madison hasn't taken any chances though, and followed one female chief of ~26 years tenure with another (with zero cook-offs).

Holy exploding billiard balls: https://en.wikipedia.org/wiki/Nitrocellulose#Other_uses
Thanks for the information. Intuition doesn't always follow the correct path.
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Old 2018-05-27, 12:32   #461
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The above-cited Wiki page says that

Quote:
Nitrocellulose, the primary component of modern smokeless powder, has a relatively low autoignition temperature of around 160–170 °C (320–338 °F)
At the Quora thread How hot do I need to make a primer for it to detonate?, we find that a common primer, fulminate of mercury, has an autoignition temperature of 338F. Incidentally, at this temp, the stuff is liquid!

So "smokeless powder" is likely to detonate at a lower temp than fulminate of mercury.

Quote:
In his book "Gunshot Wounds" Vincent Di Maio describes various experiments where ammunition was heated in ovens. He says that .22 long rifle cartridges detonate at an average of 275F, .38 Special at 290F and 12 gauge shotgun shells at 387F. The interesting thing about these furnace experiments was that in all instances the cartridge cases ruptured, but the primers did not detonate. In fact the primers were removed from some of the ruptured cases, reloaded into other brass and fired.
BTW one of the crewmen in Mister Roberts chose fulminate of mercury to make a Fourth of July firecracker, with spectacular results.

Another primer of note is Lead(II) azide. Its autoignition temperature is higher, 350C or 662F. It came up in long-ago news reports that came to mind upon seeing the subject of primers.
Quote:
Lead azide was a component of the six .22 caliber Devastator rounds fired from a Röhm RG-14 revolver by John Hinckley, Jr. in his assassination attempt on U.S. President Ronald Reagan on March 30, 1981. The rounds consisted of lead azide centers with lacquer-sealed aluminum tips designed to explode upon impact.
It seems that yet another primer, lead styphnate, has an autoignition temperature of 330 C or 626 F.

Another quora page informs us that the autoignition temperature of gunpowder (black powder) is much higher than any of these -- around 464 C or 867 F.

Curiously, the MSDS's I looked up for a couple of primers from Winchester do not provide autoignition temperatures for them...
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Old 2018-05-27, 19:34   #462
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Quote:
Originally Posted by Dr Sardonicus View Post
The above-cited Wiki page says that

At the Quora thread How hot do I need to make a primer for it to detonate?, we find that a common primer, fulminate of mercury, has an autoignition temperature of 338F. Incidentally, at this temp, the stuff is liquid!

So "smokeless powder" is likely to detonate at a lower temp than fulminate of mercury.

BTW one of the crewmen in Mister Roberts chose fulminate of mercury to make a Fourth of July firecracker, with spectacular results.

Another primer of note is Lead(II) azide. Its autoignition temperature is higher, 350C or 662F. It came up in long-ago news reports that came to mind upon seeing the subject of primers.

It seems that yet another primer, lead styphnate, has an autoignition temperature of 330 C or 626 F.

Another quora page informs us that the autoignition temperature of gunpowder (black powder) is much higher than any of these -- around 464 C or 867 F.

Curiously, the MSDS's I looked up for a couple of primers from Winchester do not provide autoignition temperatures for them...
So, as long as the primer is removed, a black powder muzzle loader is oven-safe except for the self-clean cycle, ~500C, at least in regard to unintended firing by autoignition. Not so good for the wood or plastic grips, stocks, or fore-ends though, with substantial weight loss or melting occurring. http://www.ufrgs.br/lapol/thermal_decomposition_of.pdf (Police chiefs, take note.)

Thanks much Dr. Sardonicus for your informative post.
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