mersenneforum.org The Right Way to Keep Bare Gubs
 Register FAQ Search Today's Posts Mark Forums Read

2018-05-23, 15:23   #452
kriesel

"TF79LL86GIMPS96gpu17"
Mar 2017
US midwest

13×373 Posts

Quote:
 Originally Posted by science_man_88 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).

2018-05-24, 00:25   #453
Xyzzy

"Mike"
Aug 2002

2·29·137 Posts

Quote:
 Originally Posted by kriesel The reason AR-15's are popular with that pathological group may be because they're inexpensive.
And they are everywhere.

 2018-05-25, 17:39 #454 Fusion_power     Aug 2003 Snicker, AL 7×137 Posts 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?
2018-05-25, 17:40   #455
retina
Undefined

"The unspeakable one"
Jun 2006
My evil lair

22·32·167 Posts

Quote:
 Originally Posted by Fusion_power Are we becoming more insane?
It sure looks that way.

 2018-05-25, 19:06 #456 retina Undefined     "The unspeakable one" Jun 2006 My evil lair 22×32×167 Posts 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.
2018-05-25, 23:07   #457
kriesel

"TF79LL86GIMPS96gpu17"
Mar 2017
US midwest

13·373 Posts

Quote:
 Originally Posted by retina 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.

 2018-05-26, 02:25 #458 kladner     "Kieren" Jul 2011 In My Own Galaxy! 11·13·71 Posts 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
2018-05-26, 15:28   #459
kriesel

"TF79LL86GIMPS96gpu17"
Mar 2017
US midwest

13·373 Posts
Easy-bake ammo and exploding billiard balls

Quote:
 Originally Posted by kladner 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

2018-05-26, 16:46   #460

"Kieren"
Jul 2011
In My Own Galaxy!

11·13·71 Posts

Quote:
 Originally Posted by kriesel 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.

2018-05-27, 12:32   #461
Dr Sardonicus

Feb 2017
Nowhere

25·131 Posts

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...

2018-05-27, 19:34   #462
kriesel

"TF79LL86GIMPS96gpu17"
Mar 2017
US midwest

13×373 Posts

Quote:
 Originally Posted by Dr Sardonicus 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.

 Similar Threads Thread Thread Starter Forum Replies Last Post ewmayer Hardware 7 2005-10-19 19:48 Angular Hardware 25 2003-03-04 15:05

All times are UTC. The time now is 00:22.

Wed Jan 27 00:22:24 UTC 2021 up 54 days, 20:33, 0 users, load averages: 3.89, 4.39, 4.23

This forum has received and complied with 0 (zero) government requests for information.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation.
A copy of the license is included in the FAQ.