View Full Version : MAJOR kaboom...
wetidlerjr
05-27-11, 06:05
MAJOR kaboom ! (http://www.ar15.com/forums/topic.html?b=3&f=118&t=538165)
:blink:
So they attributed this to the case not being crimped to the projectile properly? I don't crimp my reloads at all. Should I re-think this?
I am not buying the bullet set back theory, the way that split looks more like a barrel obstruction ahead of the chamber.
So they attributed this to the case not being crimped to the projectile properly? I don't crimp my reloads at all. Should I re-think this?
I wouldn't worry--I have a hard time believing a bullet set back THAT far into a case whereas rifle powders generally take up almost all of the available space in the case. And not to be able to generate pressure THAT high. It's slightly possible there may have been an incorrect, say doubled pistol powder charge in there, but being factory it shouldn't have happened. Headspace that badly deteriorated maybe? Perhaps a severe case (head) failure?
FWIW I've loaded coming up on 15,000 rounds of carious .223/556 loadings for practice and match use--never have I crimped one of those rounds, on the advice of my NRA HP coach. Never had any trouble yet, either.
It'd be nice to see the handguards removed to see if there was any barrel bulging from an obstruction--that'd do it every time if there was one.
I am not buying the bullet set back theory, the way that split looks more like a barrel obstruction ahead of the chamber.
kinda hard to prove that unless they pulled the case...confirmed setback and then put it back in to see what would happen.
could have been but doubtful they know 100% it was indeed setback pressure.
There is a recall on ths ammo. This is not the first KB I have read about involving this ammo.
http://www.remington.com/pages/news-and-resources/safety-center/safety-warning-recall-notice-Remington223-62Gr-HollowPoint.aspx
There is a recall on ths ammo. This is not the first KB I have read about involving this ammo.
http://www.remington.com/pages/news-and-resources/safety-center/safety-warning-recall-notice-Remington223-62Gr-HollowPoint.aspx
ouch...i didn't read the tos thread other than the o.p.
I hope someone posted it up over there...scary stuff. Makes you wonder what improper means. Too much powder, too little pwder, not enough neck tension, etc.
Lotsa folks stay away from reloading because they do not feel it is safe as factory....man, you just never know.
After reading that recall I woud almost BET the farm on an incorrect (say, PISTOL) powder. Someone fu(ked up in Arkansas it looks like. Neck tension causing this? Doubtful. Pressure excessive? Wrong powder. I do doubt Remington will ever admit to it though.
I hate the idiotic speculation that follows one of these incidents.
In before some tard says it was an out of battery firing. :rolleyes:
wetidlerjr
05-27-11, 08:25
I hate the idiotic speculation that follows one of these incidents.
In before some tard says it was an out of battery firing. :rolleyes:
Well, that won't happen now. You have spoiled the fun for some 'tard. :sarcastic:
I swear it seems like there is a rash of these lately. It is making me paranoid to go shoot.
Man, glad no one was hurt in this incident.
Heartland Hawk
05-27-11, 09:31
Wow. Thanks W.E.
I always try to stay away from this ammo because i have heard of a few inconsistencies. And this is one more.
My brother bought two boxes of Winchester super-X 64 gr SP last year and almost every round had a LOOSE bullet in the case. The slightest pressure on the bullet tip would shove it completely into the case.
So yes, manufacturers sometimes do use powders that do not come even close to filling the case. Plus there was no crimp (no cannelure), and obviously hardly any neck tension.
Fortunately when the bullet set back on the feed ramp it jammed in his LMT M4. We tried to chamber a few rounds until we realized nearly every round had this problem. Scary stuff.
See'd very simular happen once way long ago.
Upon hard inspection it was found that the bolt cam had not done its job AFA rotating the bolt to unlock.
The cam didn't shear so the carrier could just blow straight back, but it sure didn't move either due to gaulling on its sides (deep wear marks basically) which in turn kept all the gas pressure in the carrier with no place to release, so it blew the carrier apart.
It popped hard enough to rape the upper receiver simular to the pix, and also puked the bottom plate out of the magazine, rounds, follower, spring and all.
In before some tard says it was an out of battery firing. :rolleyes:
I have never heard anyone say that before...:rolleyes: would love to hear a detailed explanation of how that would work.
sigh...
~~~~~~~~~~~~~~~~~~~~~~
I gotta quick question...in general, is the AR design more robust to handle a KB compared to other combat semi's??
.
I am pretty sure that this one was discussed here elsewhere in the epic Kaboom thread we had.
I swear it seems like there is a rash of these lately. It is making me paranoid to go shoot.
No, we just have more AR's in circulation now than ever before.
My brother bought two boxes of Winchester super-X 64 gr SP last year and almost every round had a LOOSE bullet in the case. The slightest pressure on the bullet tip would shove it completely into the case.
So yes, manufacturers sometimes do use powders that do not come even close to filling the case. Plus there was no crimp (no cannelure), and obviously hardly any neck tension.
Fortunately when the bullet set back on the feed ramp it jammed in his LMT M4. We tried to chamber a few rounds until we realized nearly every round had this problem. Scary stuff.
Bullet "set-back" will NOT cause a ka-boom. While seating the bullet deeper intrudes on case volume, it increases freebore. The bullet will simply move forward until it engages the rifling at which point the volume has returned to normal. If anything, this freebore will reduce pressures. I had a lot of reloaded 22-250 that had high pressures when fired in my rifle. After some investigation, it was determined the bullets were seated long and the ogive was too close to the rifling on chambering. After seating them deeper to the correct depth, pressure dropped to normal levels and the rounds were safe to fire.
What makes low neck tension dangerous, particularly with a self loading rifle, is that when the case stops in the chamber, momentum can carry the bullet forward until it jams itself against the lands. This can cause enough of a pressure spike to destroy the rifle.
If the ka-boom was due to low neck tension, it's not because the bullet was pushed back into the case, it's because the bullet slid forward in the case on chambering and was jammed against the rifling, causing dangerous pressure spikes
I second that - that is exactly the cause of those types of kabooms. Thank you for stating what should be obvious to anyone who reloads an autoloader. It seems imperative now that we all inspect our factory ammo BEFORE shooting every time. Down right scary from any American manufacturer.
Lotsa folks stay away from reloading because they do not feel it is safe as factory....man, you just never know.
Thats why I load everything on a single stage, weigh every powder charge individually, measure individual case lengths and measure COL for EVERY round.
My question is this:
Neck tension is mentioned quite a few times here, so how is it measured exactly? I have noticed that on my press, 9mm takes more pressure on the lever to seat the bullet than .223/5.56 (I assume because of the difference in bullet diameter?). Every once in a while when I load .223 I will have a round (maybe 1 in 50 or 1 in 100) that feels like it takes NEXT TO NO pressure to seat. Does that mean I have inadequate neck tension?
I didn't say set back causes increased pressure in a bottle neck.
A previous poster mentioned it might be a cause of the kaboom. I was commenting that I have seen incredibly shoddy bullet seating in commercial ammunition, not even the white box stuff. Not just set back but bullets that are easily pushed into the case so they rattle around.
I would never shoot my reloads if they came out that way and I sure as heck won't shoot commercial ammo in such a condition.
I didn't say set back causes increased pressure in a bottle neck.
A previous poster mentioned it might be a cause of the kaboom. I was commenting that I have seen incredibly shoddy bullet seating in commercial ammunition, not even the white box stuff. Not just set back but bullets that are easily pushed into the case so they rattle around.
I would never shoot my reloads if they came out that way and I sure as heck won't shoot commercial ammo in such a condition.
I should have also included the previous post that talked about "setback" being the cause of the ka-boom. I selected your post because it points out a problem with low neck tension with factory ammunition.
There have been other threads with folks speculating that bullets pushed deeper into the cases are causing ka-booms while ignoring the facts.
I had no intention to chide you for your post and you have my apologies if it came across that way
Does anyone reading/contributing to this thread have any engineering background and experience with materials yield and failure characteristics? I'm curious as to what a model or someone's experience would indicate how much pressure would be needed to generate a kboom of this type?
HPT rounds are typically around 70,000 psi and they don't cause kbooms like this. I'm assuming something is terribly out of whack and this is pressure on an order of magnitude greater than a standard round. I don't think overcharing a case, or bullet setback, or insufficient neck tension (unless it's a contributor to something like SEE) would do it alone. But I do wonder if we're looking at something that generated pressure on the order of 90-100kPSI or greater to generate something like this.
Thats why I load everything on a single stage, weigh every powder charge individually, measure individual case lengths and measure COL for EVERY round.
My question is this:
Neck tension is mentioned quite a few times here, so how is it measured exactly? I have noticed that on my press, 9mm takes more pressure on the lever to seat the bullet than .223/5.56 (I assume because of the difference in bullet diameter?). Every once in a while when I load .223 I will have a round (maybe 1 in 50 or 1 in 100) that feels like it takes NEXT TO NO pressure to seat. Does that mean I have inadequate neck tension?
I would measure the outside diameter of a sized neck, and then measure the same cartridge, i,e,m that round loaded. Try your best to measure at the same point on the enck in both instances, use the headstamp as a reference point when positioning your micrometer/caliper.
I used a Lee resizer, and initailly it produced only a .001-.002" difference. I have no idea what that equates to in pounds of pull, but I wanted a larger delta between the two to indicate a greater degree of grip. I then used a stone followed by crocus cloth to polish the expanding mandrel down to the point where I achieved .003" difference between the two, and IMHO that is adequate neck tension, especially if augmented with a light crimp.
See'd very simular happen once way long ago.
Upon hard inspection it was found that the bolt cam had not done its job AFA rotating the bolt to unlock.
The cam didn't shear so the carrier could just blow straight back, but it sure didn't move either due to gaulling on its sides (deep wear marks basically) which in turn kept all the gas pressure in the carrier with no place to release, so it blew the carrier apart.
Was the case intact? No damage to the extractor? No brass colored residue blown on the bolt or carrier?
jmart, the pressure needs to be enough to make the brass case flow under the extractor and fail. The pressure escapes under the extractor, into the carrier and magwell.
jmart, the pressure needs to be enough to make the brass case flow under the extractor and fail. The pressure escapes under the extractor, into the carrier and magwell.
Assuming a new case that's drawn to normal specs and properly hardened, any idea what the resultant pressure would need to be to generate the case failure and subsequent receiver failure that you described?
yikes...those are some scary pics
Was the case intact?
Yes. Primer still seated also.
No damage to the extractor?
No
No brass colored residue blown on the bolt or carrier?
No
At the time it was likened to an engine cylinder blowing out due to coolant coming in and making hydro~lock while the revs are up: pressure blows out at the weakest point, the cylinder wall.
This is represented by the carrier in a DI rifle.
Bolt w/rings is the piston.
While not an uncompressable liquid coming in, the actual volume of gas is way more than the small cylinder area of the bolt/carrier can accomodate.
(volume of tube + expansion rate + time it takes for pressure to relieve as rounds makes its way from gas port to exiting muzzle)
Think turbo or supercharger set up for too much pressure.
If the bolt doesn't move and the gas key doesn't pop, the pressure has to go somewhere even if it means bursting the carrier, gas tube, barrel or key.
Whichever lets go first.
Teaching for a local community college for the LEO and Correction classes they offer I have seen numerous issues with factory ammo. Primers in backwards, sideways, none at all, or numerous hits with several guns and the primer doesn't go off. Bullets just plain placed anyway you can think. 357's in 38 boxes.
And I just laugh at the indoor ranges that want only factory ammo only. I guess that if it is man made man will screw it up some how:mad:.
Dan
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