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Thread: Kaboom :-\ . 223 pics and video

  1. #41
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    JonB_in_Glencoe's Avatar
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    Quote Originally Posted by BeeMan View Post
    I had to look up Nick Harvey, as I was not familiar with his load manuals. In any case, best practice is to always consult at least two sources. Since multiple sources apparently list more than 24 grains with a 55 gr bullet, getting a straight answer on just charge weight could be frustrating. Better to be frustrated than lose or gun or get hurt though...

    Some day I might get around to writing up an analysis of load manuals, the various ways they get the data, how they format it for publishing, and most importantly, why data changes. To do the subject justice would probably take a few thousand words, manual excerpts excluded. Adding the sidebars about how powders combust, variables in components, differences in instrumentation and test platforms, and how data is presented would likely double the effort. And yes, there would also be a sidebar discussion of whether lawyers have dictated lower load levels or if we just better understand the details than in the 'good old days.'

    Back to the topic at hand - assuming the firearm mechanism still functioned as designed after ~2k rounds in service, this was an over pressure event that grossly exceeded the yield point of the brass which at the moment of firing is little more than a gasket. As Larry et al have said, proper malfunction clearing procedures would have made the difference for a squib. Preventing a reload problem requires more attention at the reloading bench.
    I'd be interested in your analysis of load manuals (when you do the write up). I only searched out and posted the Max loads from My two favorite manuals and Hodgdon, because 25.5gr stuck in my mind... as that's my pet load for a CZ-527 chambered for 223rem, of course I worked up from suggested start load.

    I stumbled onto Nick Harvey (an Australian) reloading manual when I loaded my first Rifle rounds (280 rem) using Hawke's Bullets (they use a thicker soft copper jacket and pure lead core), they recommended the Nick Harvey Manual, He generates his own data. I really like it for comparison purposes and it has more European calibers than most American manuals. You can never have enough paper reloading manuals.
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  2. #42
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    None really taken Beeman.

    I was thinking, those Berry bullets might be softer. I've never shot them, are they? What is the alloy inside the plated jacket? Maybe just a primer would throw a Berry bullet up the tube further then a conventional jacket/core swaged bullet. They certainly do a cast bullet. The furthest up the barrel bullets with just a primer I found were most always in a revolver.

    If there was a bullet up the bore and another round fired behind it that would do what we have seen. The weak area on the AR bolt is at extractor. The reason for that is that actually that is were another bolt lug would be, but that can't be done because the extractor has to be there. So when the high pressure hits the bolt it actually tilts the bolt tilting it the most at the extractor. Now we're talking tilting in the thousandths of an inch, but with that kind of high pressure it doesn't take much to blow the case in that area near the extractor. I've not known anyone that blew an AR that gas came back along the carrier/bolt group and blew gas in their face because it really can't do that. In that sense I feel AR are more safe then bolt action rifles. I'd say when blow ups happen between the two types of actions that the bolt guns are less forgiving. AR's almost always dump the gas down the magazine well.

  3. #43
    Boolit Grand Master popper's Avatar
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    The AR firing pin barely protrudes from the bolt face and it doesn't do so until the bolt is in full battery and fully rotated.
    Sorry, that is a myth. DPMS (pre-buy-out) factory 308 carbine. Shoulder just a hair too long. 40.5gr 4895 under a 165 cast. Safety ON and trigger NOT pulled. Nice chunk of concrete missing. Nothing through my shoulder, did take a long time before a naughty work came out. Gun is OK so I do the same experiment with just a case sized the same. Won't go into battery - i.e. no lug lockup. Brass is LC07 MG fired. I've learned to run it 2x in the sizer. I check for high primers. Don't depend on a dwg. or mfg. for 'fail-safe'. look at the pics. Bottom of carrier is GONE. Bolt has extra 'dent' in it.
    Last edited by popper; 09-18-2017 at 08:37 PM.
    Whatever!

  4. #44
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    Quote Originally Posted by popper View Post
    Sorry, that is a myth.
    Easy enough to test with a primed case. Chamber the primed case and pull the charging handle back until the bolt rotates slightly and pull the trigger.
    Last edited by M-Tecs; 09-18-2017 at 08:33 PM.

  5. #45
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    popper your AR was out of spec. I'm not overly fond of the first series of DPMS. Haven't had a chance to inspect their Gen II. That's part of what I'm talking about in building AR's, knowing that ka ka, and what to do about it.

  6. #46
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    Quote Originally Posted by popper View Post
    Sorry, that is a myth. DPMS (pre-buy-out) factory 308 carbine. Shoulder just a hair too long. 40.5gr 4895 under a 165 cast. Safety ON and trigger NOT pulled. Nice chunk of concrete missing. Nothing through my shoulder, did take a long time before a naughty work came out. Gun is OK so I do the same experiment with just a case sized the same. Won't go into battery - i.e. no lug lockup. Brass is LC07 MG fired. I've learned to run it 2x in the sizer. I check for high primers. Don't depend on a dwg. or mfg. for 'fail-safe'. look at the pics. Bottom of carrier is GONE. Bolt has extra 'dent' in it.
    What caused the gun to fire?

  7. #47
    Boolit Grand Master popper's Avatar
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    Slam fire due to bad HS I assume. IIRC, I tossed that brass but saw no damage to it. I've gone through >500 rnds since then, no problem. Found case a LONG way from incident. Also had a total case head separation in 40SW. Recovered the case head, no burn marks on the brass. No damage to the gun which jammed next rnd on the case left in the chamber. It was a recalled lot of FC brass I must have picked up at the range. AR design is good but not fail-safe. My 300 BO bolts and the other DPMS will do the same thing - bolt starts to lock & fp WILL move. Out of spec? Unless each and every part is measured and verified, all are 'out-of-spec'. IIRC the OP said he was shooting 60gr, not 100.
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    Whatever!

  8. #48
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    Popper

    Did the primer show a firing pin indent?

    My AR 10's have firing pin springs. Does the DPMS?

    AR 10's are not standardized like AR 15's
    Last edited by M-Tecs; 09-20-2017 at 02:47 AM.

  9. #49
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    popper, first off NOTHING is fail-safe, especially when a human made and is operating it. Here's a little thread from a popular forum on firing pins and bolts. Notice CMMG participated in it and they are a major AR manufacturer. Also consider how many people make AR componants. For example the receivers...a CNC milling machine will make them. Could be done out of your garage. Anyways here's the link, read it: https://www.ar15.com/forums/ar-15/-/118-552200/?page=1 I repeat it's an interesting read and I personally don't hold AR15.COM has the absolute supreme intelligence, just as people feel about wikipedia.

    Now I spoke with Berry Bullets on the phone this morning. Their lead alloy core in their 55 grain FMJ bullets, that the op used, are of a soft alloy. They would not state exact composition. So it's may be possible the primer and no powder case may have popped it into the bore far enough for another round to chamber. I think it was Beeman that was interested in what Berry had to say about the bullet, so here you are sir.

    popper...specs and out of specs is one the differences between upperline AR's and the el cheapo's. Remember also that AR10's were never mil-speced, only the M16 and they claim AR15's since most of it's componants are compadible with M16's.

    Finally...I agree with M-Tec's post on slamfire.

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    BeeMan that all sounds very good, except for one thing still bothering me. That is how normal the primer looks. I've seen a few scenarios that look exactly like the op's, but one big difference....the primer was GONE! A very high percentage of these incident seem to blow the case at the extractor side. I mentioned previously about the bolt tilting that way because of the lack of a bolt lug on that side to make room for the extractor.

    I believe the M197 chamber pressure high pressure test is about 70,000 psi. Little interesting chart:
    M193 Chamber pressure...............52,000 psi
    M196 Chamber pressure ..............52,000 psi (tracer)
    M197 Chamber pressure...........70,000 psi (high pressure test)
    M855 Chamber pressure ..............55,000 psi
    M856 Chamber pressure ..............55,000 psi (tracer)
    M995 Chamber pressure...............50,250 psi (armor piercing)

  11. #51
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    With a bullet stuck in the throat, leade, etc. an AR bolt/carrier when drawn to the rear and released has sufficient momentum to push the next feeding bullet back into the case. I saw this many times over the years even with M193 and M855 ammo. It is particularly noticeable in FTE (failure to extract) where the fired case stays in the chamber, the action functions and the bullet of the feeding round is stopped by the case in the chamber. That bullet invariably gets pushed back into the case. In those instances the round will not chamber of course.

    However, in the OPs case the soft jacketed bullet stuck in the leade was probably push a bit further into the bore while the bullet in the feeding cartridge was shoved back into the case. That in essence created a "110 gr bullet" (the combined weight of the 2 bullets) over 24 gr H335......obviously not good!

    BTW; 24 gr H335 under a 55 gr bullet is a medium range 223 Rem load. It takes 25 - 25.5 gr to make the SAAMI MAP. It takes 26.5 to 27 gr to equal the 5.56 MAP. My standard load since the mid '70s has been 26.5 gr H335 in LC cases with a WSR or CCI 450 primer under a 55 gr Hornady SX (12 and 14" twist barrels). The measured psi (Oehler M43) in a 223 Rem chamber runs right at 59,500 to 60,000 psi.

    Note; the psi I give are transducer/gauge psi's. The previous post psi's are CUPs. I'll also add that M193 made since around 2003 or 4 has the same measured psi as M855; 60 to 62,000 + psi. The older M193 ran around 58,000 psi which is about 4,000 +/- psi more than most 223 Rem factory cartridges are loaded to.
    Last edited by Larry Gibson; 09-19-2017 at 11:58 AM.
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  12. #52
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    First off... I am glad that the OP was not hurt, nor anyone around him during this "event".

    Secondly, "Many Thanks!" to all of you knowledgeable folks who are participating in this discussion. I am learning quite a bit from it & although an "AR" is not in my possession at this time, but likely may be in the future... my days in the Corps, using an M16A1 & knowing its' components, has allowed me to follow the discussion so far. Even if one doesn't have any knowledge of the workings of the AR15, or the M16 platform, there is a good bit of knowledge to be learned from these posts in this topic, IMO. Particularly the bits about safety & focus in reloading & safe operations of firearms(particularly regarding FTF) that are applicable to this "event". Thanks again for your sharing!
    Last edited by JBinMN; 09-19-2017 at 12:05 PM.
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    I'm impressed that if it was essentially two bullets being fired that the bolt lugs didn't at least crack. I sure would like to know what the barrel looks like especially where the bullets were located before firing. Like I've mentioned I've seen a lot of AR blowups and a high percentage of the time the shooter walks away uninjured. How many shooters I've seen that had a blowup on a bolt action wood stock getting injured from wood splinters.

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    Larry if you're talking about my psi's being cup, that is not what I find. Those come from the TM43-0001-27 Army manual and are on page 10-9 and listed as psi. Here's the pfd link to the manual: http://pdf.textfiles.com/manuals/MIL...april_1994.pdf

    For those of you that haven't read this it's an interesting read.

  15. #55
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    Yes the pressures are listed as "psi" but they are measured via CUP method. All older published pressures taken via CUP and LUP were refered to as "psi". However, with the advent of modern and better pressure measuring methods (transducer and strain gauge) the older CUP and LUP measurements are refered to as; CUP or LUP. Transducer and strain gage measurements are now referred to as "psi". Some newer manuals such as Lyman's uses and denotes both types of measurement. Also SAAMI lists pressure specs for both types of measurement.
    Larry Gibson

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  16. #56
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    Previous TMs had definitions and testing procedures. Also the pressures listed are MAPs (Maximum Allowable Pressure). That is not necessarily what any lot of cartrdges is actually loaded to. Cartridges are loaded to a +/- velocity spec not to exceed the MAP.
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    Larry I just merely posted what I did to give a generalization of what kind of pressures are dealt with in the 223/5.56, although we can't be certain what the op's pressures were. We would have to pressure test his ammon in pressure testing barrel because as you very well know it's you can't do it on a AR unless it was a special model just for pressure testing. You sure can't get a strain gauge over the chamber an AR. BTW the Army correlated those psi figures. There is an error factor in both systems, I believe CUP runs as high as 3000 psi error and piezo has much less error in the 1300's psi range. Both have to take into account what the cartridge case wall changes except in I believe CIP which a hole is drill eliminating having to deal with what the case wall would change.

    We unfortunately have gone off track and I apologize. Larry I still would like to hear from you why the primer of his culprit case looks pretty normal if indeed two bullet were fired.

  18. #58
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    Please don't misunderstand, I was not being critical at all. I was just explaining the why the psi (CUP) figures you posted were different than the psi I posted. It's like driving your car about 60 MPH, your also going about 100 KPH......same speed just a different method of measurement.

    I measure psi via a strain gauge and a M43 Oehler PBL. It is on a very tight chambered (223 chamber) Contender Carbine barrel. BTW; it's not an "error factor" correction but in terminology we use today is an ES (Extreme Spread) or a =/- specification. The transducer/gauge psi measurement systems are considered more consistent and give a much better "picture" via a pressure trace. That is why most manufacturers use the newer system. NATO spec ammunition is also measured with a transducer mounted at the case mouth. They can then measure psi's on actual AR barrels. However, such measurements generally produce slightly lower psi's and somewhat different pressure traces.

    "I still would like to hear from you why the primer of his culprit case looks pretty normal if indeed two bullet were fired."

    I can't say that the primer "looks pretty normal" from that picture. It appears to be severely flattened with the primer pocket completely blown. I can't discern if part of the primer was also blow out where the case head was blown out. Note the severe case extrusion into the ejector hole; that only happens from extreme pressure. Given other severe damage such as the cracked bolt carrier and the swelled receiver are also indicative of extreme pressure.

    Watch the video carefully paying attention to the sequence of events prior to the ka-boom.

    Note the recoil of the rifle when fired during the previous target engagements.

    Note, when the FTF occurs the non recoil of the rifle, just a click heard and no impact down range.

    OP then clears the supposed FTF cartridge by pulling back on the op handle and letting go of the op handle so the bolt fed and chambered the next round on it's own.

    OP then pulls trigger and the ka-boom then happens.

    My conclusion; The supposed FTF was not a FTF; it did fire except there was no powder in that case. The force of the primer pushed the bullet into the leade where it stuck. When the OP extracted the supposed FTF cartridge he actually just extracted a fired case. When the OP let go of the op handle (pulled fully back) the recoil spring drove the next cartridge from the magazine into the chamber. The momentum of the bolt carrier/bolt drove that cartridge completely into the chamber and the bolt closed. On chambering the bullet of the chambering cartridge struck the rear of the stuck bullet and may or may not have pushed it further into the bore. The bullet in the cartridge was driven back into the case. At that point there was 110 gr of the combined weight of both bullets in front of 24 gr H335 in the cartridge, a gross over load. The OP pulled the trigger and the rest is as they say......history.
    Last edited by Larry Gibson; 09-19-2017 at 03:46 PM.
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  19. #59
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    Larry, oh no no no, there's no mis-understanding at all. We're on the same page there.

    I blew up that case head photo. Look at it, that primer still has a round edge. I've seen much much flatter primers from excessive pressure then that. Kind of like you troweled cement in the primer pocket. I totaly agree with you on the extrusion of the case head into the ejector hole. My theory on the primer is that the case blew, also blowing out much of the primer pocket as you noted, thus releasing the high pressure from all of it being on the primer. I feel the carrier cracked mainly from the gas pressure blown into it from the blown case. The bolt took all the pressure and much of it off the carrier. Only pressure imparted to the carrier on an AR is 1. gas pressure from the gas tube and 2. some force from the bolt through the cam pin. Do we know if the bolt openned? If it didn't open then no force on the cam pin. I don't know how much pressure there was in the barrel at the gas port, thus don't know how much gas pressured entered the carrier cylinder area. Like I said I think the carrier busted from the eruption of the gas out of the blown case.

    I'm very thankful of the Lord the op didn't get hurt and thank Lord again his eyes are okay. It's a shame to have learned a lesson the hard way.

    Here's the pic:

    Click image for larger version. 

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    Even the primer indentation isn't flattened excessively, nor did the primer try to flow in the firing pin hole.

  20. #60
    Boolit Buddy Prospector Howard's Avatar
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    I do believe the talk about 24gr of H335 behind 110 grains of projectiles is a red herring. I don't care if the stuck in the bore item is 10gr or 55gr, once you fire the new bullet into anything that is lodged in a barrel as tight as that first 55gr projectile, you're going to have a blown up rifle.
    Last edited by Prospector Howard; 09-19-2017 at 07:18 PM.
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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check