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[ARCHIVED THREAD] - what went wrong? (Page 1 of 2)
Posted: 5/25/2008 12:44:06 PM EDT
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I would like your opinions and not the flame types. m16 10 1/4" barrel reload: rp 223 rem brass, 26.0gr wc844 lot 71706 , m193 bullet , no. 41 primer lot b02zc        thanks GMBs123 |
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Offhand, I'd say you overcharged that particular round. Didn't check the data, but that's what the case looks like. ETA: I don't think headspace would've blown the primer out, and misshaped the rim and primer pocket like that would it??? Not too sure, but if nothing else....Tagged for verdict. I'm curious. |
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Is there any chance that the powder measure had some faster powder left in it from a previous loading setup, because It looks like a faster powder than WC844 did this. How many of these loads did you try from this batch. If you have some left I would pull a couple down and see if the powder charge checks out as far as weight and appearance compared to a sample of WC844. Another possibility is that the WC844 powder got mixed up with another type of powder. I would not fire any more of these until it is sorted out, that is one hell of a over pressure situation. Stay Safe Joe |
Just wow!!  Given the brass flow resulting in the extractor and ejector impression (among other things), I’ve gotta think it was overpressure - and a lot of it. Course, the primer doesn’t appear to be flattened!  I guess a really soft case head might do this too. |
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I am no expert and I may be stating the obvious. It looks to me like it fired out of battery. If that is the case (no pun intended), it may not be a over pressure situation. It looks like the rear of the case was not supported by the chamber causing it to expand and as a result, blowing the primer out. If it was an OOB discharge, I would be concerned about why that happened. You said that it was an M16, just out of curiosity, were you in "rock and roll" mode when it happened? Joe |
Severe overpressure will accentuate miniscule dents, dings, etc. You're right, it does appear to be well used, but looking at it in a pic may not be indicative of how worn it really is. |
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It appears to have had excessive headspace. Was this round put into a case gauge (dillon, wilson) after sizing? Yes, Wilson pretty sure. Pretty amazing pictures. At first I thought that I was looking at a belted magnum round. Any chance that you over charged that round? No. Loaded it on a Dillon XL650 with powder check station. Is there any chance that the powder measure had some faster powder left in it from a previous loading setup, because It looks like a faster powder than WC844 did this. No. How many of these loads did you try from this batch. @45. No signs of excessive pressure. If you have some left I would pull a couple down and see if the powder charge checks out as far as weight and appearance compared to a sample of WC844. Another possibility is that the WC844 powder got mixed up with another type of powder. I would not fire any more of these until it is sorted out, that is one hell of a over pressure situation. Stay Safe Joe I shot 7 more through a 20in. bbl. over a CED chronograph. @ 2950fps I have shot full power (28.0gr. 3200fps.) without incident. Given the brass flow resulting in the extractor and ejector impression (among other things), I’ve gotta think it was overpressure - and a lot of it. Course, the primer doesn’t appear to be flattened! I guess a really soft case head might do this too. That was my thought too! I am no expert and I may be stating the obvious. It looks to me like it fired out of battery. If that is the case (no pun intended), it may not be a over pressure situation. It looks like the rear of the case was not supported by the chamber causing it to expand and as a result, blowing the primer out. The firing pin struck the primer, so it must have been in battery. Also the bolt was still partly locked when it jammed. If it was an OOB discharge, I would be concerned about why that happened. You said that it was an M16, just out of curiosity, were you in "rock and roll" mode when it happened? Joe Yes.  That's what stopped the fun!! |
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I have a barrel sitting here next to me with a live round in it, just a barrel and round. The chamber supports the round/case to the extractor rim. If that is the normal unsupported part, we would be seeing more KBs than G22s. Looks like (as someone else said) firing out of battery to me. As to the FP hitting it, that could happen if the FP was stuck in the out position, such as bent, or trash or carbon in the hole keeping it from moving. Has happened before. (has even made semis go double at times) Is it an M16 or host with RDIAS? If RDIAS, you may want to check timing on your paddle, and clean your bolt. Good luck. BW ETA: needmoreammo, no biggie, we're all here to try to help when we can  take care |
M16. Timing is good, firing pin is also good. Bolt carrier was clean when I started, 77rds ago.
Yes.
The bolt/bolt carrier was clean so I don't think the firing pin stuck. Also, even if it had, the bolt carrier is designed, such that the firing pin will not penetrate the bolt face unless the bolt is locked.
Sounds about right. The case OAL was 1.77in. I trimmed it to 1.75in. My opinion is that it was a soft case. The primer was struck but not deformed so it could not have been OOB or over charged/obstruction. |
| Yes the primer does look ok so that would lead one to believe the brass was weak but wow. That's scary. If the pressure was really high the primer should look deformed. Man I hope we figure this out. I use wc844 also and the primer looks correct for 26g. Do you know the history of the brass? |
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I don't KNOW FOR SURE................ But, does that flash hole look "large" to you? Could someone have used a drill to enlargen it? Humm, then when it went off.........the pressure besides pushing the bullet forward...........would also be pushing back against the primer with greater than usual force. But then, the case would have still been contained by the locked bolt and chamber walls..........so, it would NOT look like a "belted magnum case." But, since the force was also rearward at a faster than usual rate...........then that may be a reason for a possible premature unlocking and the subsequent damage and "belted" look. I'd check the lugs of the bolt and barrel for damage. BUT, I could go with, "out of battery discharge," and, move on from there. Aloha, Mark |
| an ar15 wont fire out of battery. the carrier has to move forward enough to spin the bolt closed before the firing pin will protrude from the hole in the bolt face. If you pull the trigger on a out of battery round the hammer will fall but the firing pin wont come through the bolt. Not until the carrier move forward enough to spin the bolt closed. |
No. Except that it is history. |
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Obviously the only way you can get the belted expansion of the case is if it is outside of the chamber when it goes bang. That being said, I have personally seen out of battery Kabooms on two different Bushmaster uppers. In one case the upper was ruined in the second it only blew out the magazine. Bushmaster was aware of the problem and replaced the upper and bolt on the first and replaced the bolt on the other. Glock9 |
Except to say that.........the firing pin could have become stuck in the bolt (due to crud, bent or other reason). Then, the bolt picks up a round and as it's traveling forward, because the pin is already out, it strikes the primer and sets off the round, before it's properly chambered. But, I would also expect to see the neck "blown out," or a shorter than usual neck length. So, may be it was partially in the chamber? Anyway, IIRC the OP said, he was on Full Auto when this happened. So, IF the round went off totally within the chamber w/ the lugs locked.......I wouldn't expect to see a "belted magnum" looking cartridge case. Aloha, Mark PS.............can we get some measurements? Total length, length to shoulder, width of case at various points? |
The way the rim has extractor pull marks  I would say the round fired somewhat normally but was extracted while pressure was still high. This would explain why the case was not ruptured the way they do when ignited out of battery.I noticed in pic #6 that the "belt" that was formed has an obvious taper to it. Could have been formed while the case was on it's way out of the chamber. How a case can be extracted before the pressure in the barell lowers almost seems impossible though. And yes, I did drive by a Holiday Inn last month after the sun set. Edit: Severe overpressure might have caused the bolt to unlock after the bullet went past the gas port but before it exited the muzzle. This could be why the case was able to be extracted the length of the expanded head. The primer blew out when the bolt unlocked. |
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Some where long, long ago, far, far away, I've seen pics like this before,, it was a case fired with oil on it,, maybe Hatcher's note book, or some other book I've read in the past. A couple of questions. Did the case have any oil or grease on it when fired? Could there have been any water or oil in the chamber? I would really, really check over the headspace, bolt lugs, and barrel extension lugs closely on that upper. 'Borg |
Hatcher's Notebook. Referring to match shooters that were putting grease on their bullets during a match. Blew up a Springfield no less! |
I agree with your assumption. If the brass was still fully in the chamber then a split or the bright ring close to the web of the brass would be evident. Also a blown out primer. |
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Someone up the thread said: "...the rear of the case was not supported by the chamber ..." That is correct. In an AR15 arrangement, the rear of the case is not supported by the chamber. See for yourself. Take the upper off. Slide a round into the chamber, and take a look. I also agree with the one who said the RP brass saved you from having a really bad day. That is some kind of tough brass to hold together with that much overpressure. STOP SHOOTING! My guess: Too much or wrong kind of powder, or casing neck too long and jammed into chamber leade. PS: If the rough surface on the outside of the RP casing in the photo is typical of the brass fired through your M16 10.5" bbl, then the chamber is completely hosed and probably beyond repair. Save up your big mac money now for a new chrome plated chamber and bbl. |
The firing pin's forward travel is limited by the bolt carrier. Therefore if the firing pin stuck in the bolt, the bolt would either not lock or not unlock.
If the neck trim was missed, and that round was loaded into the chamber with the 1.77" casing oal, then it is entirely possible that the end of the crimped neck was trapped in the cannelure when the bolt closed. Upon firing both the brass neck and bullet would then try to extrude down into the bbl bore. This could result in overpressure. I was surprised at how little clearance there is on my Bushy and Colt chambers for handling trimmmed brass over 1.760 ie., none. On the other hand, that long neck may have been generated by the near KB by some other mechanism. |
That's strange,,, out of the 8 or 9 Colt chambers that I've done chamber casts,, all had over .030 clearence, in the 1.790 range. How are you measuring your chamber? 'Borg |
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I saw this today and was thinking (dangerous)........pics and entire quote, can be seen at............ www.radomski.us/njhp/cart_tech.htm
So........could the extraction have occured while there was still DANGEROUS pressure involved? (Aka: Out Of Battery) Thus, the blown out "belted magnum" looking case and the excessively dirty cases. Remember, this occured while in full auto. So a certain amount of "bounce" could also be involved. Just my .02. Aloha, Mark |
I use the Sinclair method with a modified RCBS precision micrometer for gaging. After posting the article, some others here went back and checked their chambers and got the same results. How do you do your chamber casts to get the 1.790? |
| Related read here, Don't Crowd Cartridge Case Trim Length Not much forgiveness in chambers past 1.760" |
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Before I even put the barrel on an upper, I push a patch down the bore to where it's in the rifling about a 1/4 inch, then pour molten Cerosafe in the chamber. Let harden, then push out from the muzzle and measure. That way I get a total visual on the chamber, leade, and everything in between,, doing it with a rigged up affair may not give you the true measurment. 'Borg |
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So I was reading this article......... www.jouster.com/articles30m1/M16part2.html And, it got me thinking......maybe it's a multitude of "issues," working together? Humm.....barrel length, chrome chamber, gas pulse, pressure curve, powder type, particular lot#, buffer weight, etc......... Maybe, it ain't so simple as a, single cause. Anyway, perhaps, something to think on? And, note what was said about, "Slam Fires." For those that say, "It can't happen." Aloha, Mark |
That's what I thought too looking at the pics. That case looks like shit to begin with, looks like it should have been trashed. I can't say exactly what happened, I'm by no means an expert ... we need more details about your reloading practices. |
Dude, all those cases look horrible! I've never seen a fired round look that dirty, were they cleaned at all before reloading? Are you being diligent about your case inspection? It kinda looks like you're using cases that should have been trashed long ago ... you can see the beginnings of case/head separation on the far right 'good' case. |
[ARCHIVED THREAD] - what went wrong? (Page 1 of 2)
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