Interesting kB info

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[ARCHIVED THREAD] - Interesting kB info

Posted: 1/5/2006 2:04:42 AM EDT

benchrest.com/forums/showthread.php?t=5064&page=3

Quoted:
Stress Relieving the other end

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Oh by the way, if you are using GI brass it is a little safer from the user standpoint because you are assured the case went through the flames in the upright position. We used to get a M16 in about every eight months that was "blown". No catastrophic bolt failure, no failed barrel, case head basically vaporized and gas let go around locking lugs expanding upper group, blowing the magazine out, causing the kid to do things in his drawers not planned on. We never could prove what was what because they never sent the round in from the field. It is known that once in a blue moon (Southern Saying) a round goes through the flames upside down and now you have a soft head condition. This is absolutley guaranteed to ruin you day, most of the week and be remembered forever.
There are procedures to be followed with a catastrophic failure, only problem is they don't pass it down to the troops. Every time I saw one, the pieces were taped back together, no brass sent in and very sketchy details. I once had a conversation with a Captain who explained when I kid gets hurt, the COs tend to think it will reflect poorly on them and they shall we say are not forthcoming. Don't tell, don't explain etc.
As you know gov't brass is not polished to clean it up so you can look/see if the head is blue. That is the one you don't shoot.At the commercial plants the marketing boys have determined "everyone wants pretty bullets" so they tumble them after case fab to make'em pretty.
So if one goes through upside down you won't know till you touch it off. Did someone say anything about safety glasses?
We used to have a saying in the Small Cal Lab, a fired case is a proofed case if it is commercial.
It was estimated one goes though the flames upside down about every 30 million or so. I think that was arrived at by estimating the number of rounds fired by the number of guns coming in "blown".
But then there was another time a M16 came it. We could not see down the barrel so I took it over to the large cal inspection facility and x-rayed the barrel. There was this 55 gr. M193 projectly stopped still in the bore with little or no deformation. Nose to nose was a cleaning rod jag and patch inserted from the muzzle. There was no visible expansion of the barrel at that point either, but the case head was gone.
I believe the estimated vapor pressure is like 115,000 lbs.All in all US ammunition is the finest in the world.
This is the reason Marty Tyska told me to hold cases in fingers while rotating other end in flame. I think the pain threshold is like 140 deg so you haven't gotton things out of hand. Anyone that does not think a case gets hot hasn't had the sublime pleasure of getting one down his neck from the shooter on the next point. I shot a M16 left handed with no shirt on from the hip once and all three cases printed perfect second degree burns on my stomach to the point you could see the shoulders/necks imprints right before the blisters appeared. First only and last time I did that. I got smarter like the kid with the hot horse shoe, just doesn't take long to look at them. There has been at least two incidents where GI's have got hot brass down the collar in the standing position and in their haste to get away from the case whirled around and shot the firer on the next point by accident.
I like the lead method for uniformity only thing is I don't like the lead fumes.

Origially Posted by Humpy:
Hot cases, good times tonight!!!!!!!!

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Got to think about it this way. With a semi auto or full auto the case is extracted BEFORE it has time to conduct most of its heat to the chamber wall.
Internal temperature on ignition is 2500 to 3000 deg F.
On a bolt gun the heat transfers to the barrel before you can open the bolt. After rapid fire in highpower they can get still warm but NO ONE picks up one right out of a M1A/M14.
The interesting test is the cookoff test. One shot per second for 500 seconds. On mag rifles during magazine change of course they lose a couple seconds and they speed up to catch up to the sequence of one per second.
Thermocouples are placed on the barrel. ON the M16 barrel temps got to circa 450 deg F and the 501st round is chambered and the stop watch is started. Cookoff was achieved in 8 seconds if memory serves me correctly.

Good news on M16 they generally don't have barrel failure because the gas tube turns to sphagetti and rifle shuts down. On M14 it was different. We got a round through the side of the barrel at 278 rounds of continious full auto.

In our simple world of bolt guns we don't experience the problems that can be encountered when technology takes over. The good news in all this is the brass is not at temperature long enough to rearrange the grain structure as can be done with propane torch.

As a side note I could take a three man gun crew and run 10,000 rounds per day and never overheat a barrel. This can burn you out. We once shot 12 hours a day for fourteen straight days. That will burn you out. I used to worry about all the brass going to the dump. I have seen piles of brass that would fill a 30 gallon drum on the ground until the cages were found which made life alot easier. Then there was only a hundred or so that made it to the ground.

Posted: 1/5/2006 2:31:16 AM EDT

[#1]

really informative page

Posted: 1/5/2006 2:38:42 AM EDT

[#2]

Having seen Federal's ammo line in person (several years ago, but still), I have to wonder about the "upside down" theory. It's not possible for a round to go in by the neck, as they're held by the extractor groove and there are "bumps" that kick them out if they go in wrong way up.

Perhaps this is a newer system, or different plants operate differently, but what I saw I don't believe you could anneal one on the wrong end.

Dunno.

Posted: 1/5/2006 3:49:44 AM EDT

[#3]

One Every 30 Million! Like An Opposite Lotto.

Posted: 1/5/2006 2:07:44 PM EDT

[#4]

Quoted:
Perhaps this is a newer system, or different plants operate differently, but what I saw I don't believe you could anneal one on the wrong end.

maybe not at Federal

the numbers he gives are for USGI brass, we don't know how Wolf or whoever does it.

[ARCHIVED THREAD] - Interesting kB info

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