View Full Version : New stoppage encountered today... for me at least
First time I have experienced this one.
We were running drills today, one of my students transitioned to his handgun, and finished the drills running his pistol. Once I called the line cold, he called me over to him.
The bolt was stuck fully to the rear, in the open position. Charging handle was inoperable... Chamber clear, no bolt over brass, etc.
http://i62.photobucket.com/albums/h119/mdmccall/Range%20Time/9g.jpg
http://i62.photobucket.com/albums/h119/mdmccall/Range%20Time/9h.jpg
Bottom line, I could not for the life of me, see what the issue was. In the end, had to disassemble the rifle. Got out my tool kit, took off the stock, castle nut, removed the buffer tube, being careful since the buffer spring was compressed.
Once I got the buffer tube assembly off the rifle, I pushed the bolt forward and felt resistance. Looking all over the place with my pen light... I found the culprit.
http://i62.photobucket.com/albums/h119/mdmccall/Range%20Time/9i.jpg
Primer unseated out of the cartridge, and lodged between the bolt and the upper receiver. Very interesting stoppage... made the MIGHTY COLT stop in it's tracks.
I don't know if this is the proper forum for this post, if not... my apologies. I just wanted to share this stoppage.
I have encountered blown primers falling into the fire control group, but never wedging up between the BCG and the Upper Receiver.
Also, the operator was running iron sights for this drill.
Cincinnatus
02-02-11, 21:26
Intriguing. Thanks for sharing and the pics.
Would any sort of remedial action have cleared this or was it stuck so stiff that only your disassembly could free the BCG? What brand/type of ammunition was being used? Reloads?
Did you see where the bind point was?
Loose primers are notorious for gumming up trigger groups. Tight chambers (non 5.56) increase pressure and exacerbate these issues.
Shit ammo doesn't help either.
Neato, a new one for the book
I have had a few those happen in Iraq. A few were Bushmasters and one was a Colt.
The Bushmasters had tight chambers which was causing the primers to blow.
I had this happen to me several years ago with crappy M855. If I can recall, it was a colt BCG in a less than spec chamber.
The chamber pressure of this round is so high that it is right on the edge of doing this sort of thing on a regular basis. The higher environmental temps of Iraq are a contributing factor. This environmental temperature influence on the pressure of the round has been known to hunters in equatorial Africa for many years. We have sacrificed a significant degree of reliability to gain another 50 meters of effective range. If I were king, I would order the chamber pressure of 5.56 to be reduced by 10%.
Un-crimped primers and reloaded ammo are the worst offenders. Use only crimped primer factory ammo for critical situations.
This is an agency rifle, and the operator was using old M193 (SS109) 5.56 ammo. The cartridge case was stamped for Lake City, and according to the operator, was old training ammo that they brought to "burn up". This ammo was causing several hung cases in the chambers... and was giving light primer strikes on several of the other rifles. It was good, because those running it, were really getting their remedial action drills down pat.
The stoppage had the BCG locked up so tight, the only way to free it was to remove the buffer tube assembly.
That was a first for me.
Since the M193 was old training stock, do you think they might've stored it in too hot a location at some point? If so, that could lead to powder degradation and pressure spikes which might explain the hung cases and the popped primer.
Anyone happen to inspect this ammo before the training?
Also as a side question; isn't SS109 was green tip?
We had a huge lot of Federal uncrimped primers create havoc. Many pallets went back.
Most of the issues were in the FCG where 2 rifles went auto. However I have seen blown primers end up in the lug area and one rifle locked up tighter than a drum from a primer wedged in the cam pin cut out on the carrier.
RogerinTPA
02-03-11, 21:00
Popped primers are more common than most people think. Popped primers landing in the most weird places (Cam pin holes, inside gas keys, in gas tubes) and locking up the weapon. If you're lucky, it will just pop loose and not get lodged into anything. As others have stated, it's usually with out of specked chambers (BM, Oly, Stag, DPMS) and XM193.
Sounds like my black powder revolver!
I have heard about this but never seen one. Almost all of my shooting has been military rifles/carbines and ammo (M193/M855). Is there a known way to clear this type stoppage without disassembly?
SS109 is the actual 62gr bullet with the steel penertator. US ammo loaded with this bullet is M855. If this ammo was real M193 there is no telling why it was sold off, and what issues that particular lot of ammo might have had.
Anyone happen to inspect this ammo before the training?
Also as a side question; isn't SS109 was green tip?
This ammo was true M193. I saw the boxes.
The ammo was training rounds that the department brought to the range with them to use during the class. Where they bought it from, I have no clue. I did not ask.
How the agency stored it is also unknown to me. I dealt with the stoppage, and wanted to show it since it's the first time I had ever seen it.
We had a few students that bought some reloads with them... 55 grain... that they purchased on their own, because their agency did not provide them with ammo for the course. They had issues with the cartridges getting stuck in the chambers... but this blown primer was from the M193.
RogerinTPA
02-03-11, 21:45
Sounds like my black powder revolver!
I have heard about this but never seen one. Almost all of my shooting has been military rifles/carbines and ammo (M193/M855). Is there a known way to clear this type stoppage without disassembly?
The civilian variants of M193, start with an X, since it is illegal to sell real M193 to civilians. I honestly don't think they make real M193 anymore these days. The XM193 variants (XM193C,D, F, etc...) seems to be the main culprit in most anecdotal stories, but it has happened with other brands as well, again with manufactures to the far left of the chart, with barrels stamped 5.56, when the chambers are in fact .223 chambers. In a VTAC 1.5 Carbine class, one guy (don't remember the weapon) had so many popped primers with XM193 ammo, he couldn't make it through a single relay without getting one on TD 1. Talk about frustration and being pissed off. Lucky he was able to obtain another case of ammo of a different type to finish the last two days.
Unfortunately, if the primer get's stuck in a weird location where it locks up the gun, you will have to disassemble the weapon, remove it and inspect for damage, or you should, before operating the gun again safely.
SS109 is the actual 62gr bullet with the steel penertator. US ammo loaded with this bullet is M855. If this ammo was real M193 there is no telling why it was sold off, and what issues that particular lot of ammo might have had.
Thanks,
My point was M193 does not have a green tip and is not SS109/M855
Thanks,
My point was M193 does not have a green tip and is not SS109/M855
This M193 does not have a green tip. I was incorrect in calling it SS109 I guess. The boxes are marked M193, and the rounds do not have a green tip. I do not recall the boxes having an "x" in front either. This ammo belonged to a Federal Agency, so it was not civilian.
Sorry if I started any confusion.
Heavy Metal
02-03-11, 21:56
SS109 is not M-193.
SS109 is the name of the 62 grain green-tipped(if made in the US) steel insert penetrator projectile that tops off an M-855 round.
M-193 ALWAYS contains a 55 grain copper-jacketed, 100% lead core, full metal jacketed boat-tail projectile.
Almost sounds like the notoriously primer-popping Federal XM-193.
DMack,
Since it sounds like you were able to push the BC forward by hand, do you think it could have been dislodged by bumping the muzzle on the ground or a hard surface?
I'm thinking about possible emergency action here.
DMack,
Since it sounds like you were able to push the BC forward by hand, do you think it could have been dislodged by bumping the muzzle on the ground or a hard surface?
I'm thinking about possible emergency action here.
Redhat,
Honestly... I could not make the BCG budge until I relieved the pressure off the buffer spring, by removing the buffer tube. The rifle was locked up tight.
I was really stumped.
My first thought was that a lug had broken off the bolt, but once I looked at it closely, I could see the primer stuck up above the gas key.
This is why I posted this stoppage. I apologize if I caused any confusion in my initial post. I was very tired... long week this week.
We are going to run rifle and handgun tables again today, with some shotgun mixed in. I spoke with the operator of this rifle yesterday, and asked him to let me know if there were any other issues.
The chamber pressure of this round is so high that it is right on the edge of doing this sort of thing on a regular basis. The higher environmental temps of Iraq are a contributing factor. This environmental temperature influence on the pressure of the round has been known to hunters in equatorial Africa for many years. We have sacrificed a significant degree of reliability to gain another 50 meters of effective range. If I were king, I would order the chamber pressure of 5.56 to be reduced by 10%.
Un-crimped primers and reloaded ammo are the worst offenders. Use only crimped primer factory ammo for critical situations.
Modern powders have less problems from pressure spikes from tropical heat than they once did. Modern ammunition still exhibit a change in velocity and pressure as the ammunition changes in temperature, but it's much less of danger than it once was. The biggest problem was with British cordite ammunition in equatorial zones, stored in huts for long periods, where it had little protection from exposure to drastic temperature changes. Long term exposure to temperature changes where the highs were very hot made changes (I believe it was described as a leaching process) to the cordite that gave it very erratic performance. As a result, chamber pressures were deliberately kept low by smokeless powder standards to keep the unexpected pressure spikes from driving the bolt and other pieces of the rifle into the shooter's forehead. There was also the problem of the brass cases corroding in storage as well.
Modern powders have come a long way and are much more stable, both chemically and in performance.
While the NATO lists maximum pressure for the 5.56x45 as 430 MPa (62,367 psi) we don't really know how that compares to SAMMI pressures (SAAMI lists the pressure for the 223 to be 55,000 psi, for example). Where the pressure is measured and the type piezoelectric transducers used differs between the two specs. Each system will give it's own result when testing the same round. It is thought that the NATO method gives higher readings than the SAAMI method. While the two specs cannot be directly compared, several rounds are listed by SAAMI as having a pressure of 65,000 psi, such as the 300 WSM and other magnums and they are not notorious for popping primers even in hot desert climes.
In order for high pressures to be popping primers out, the pressure has to be high enough to cause enough expansion to open up the primer pocket enough that the primer will just fall out and that is quite a bit of pressure indeed.
Cases manufactured with over sized primer pockets (something experienced reloaders know is a very real possibility) will cause popped primers.
Reducing the pressure of 5.56 ammunition should reduce the incident of popped primers, but based on the evidence, I don't think it's the primary culprit in the AR
Well...what do you think caused it?
goneballistic
02-04-11, 10:59
I had this exact same stoppage once with reloads when we were ground squirrel hunting in about 105 degree heat on the lava rocks. We were shooting BLC-(2) which has a rep for being somewhat temp sensitive.
instead of a blown primer it was a case head piece that got torn off by the extractor, the case stuck the case head broke a piece off and flipped up above the bolt and locked it back.
it did the same thing yours did but it wasn't nearly as far back. it was locked up hard though. we couldn't get it to move either way.
finally since we had no spare gun to swap in at the time, we decided to use a rubber mallet on the FA to try and get it back into/near battery and try to disassemble it.
a few whacks on the FA with a rubber mallet and it rolled the brass over and finally came loose. it fell out and we found it.
we got it running again but had to use a cleaning rod to drive the stuck case out.
the rest of the afternoon we took a ziplock bag and put the ammo in a bunch of bags and put them in the cooler with the ice and we were fine. that's the only time I've ever had that happen.
the gun was a RRA with a free float tube a match barrel etc so it may have a tighter or non spec chamber, but I don't know for sure.
Good timing with this thread. I was reading "Green Eyes, Black Rifles" last night and it talks about this exact stoppage scenario, with the same results.
Thanks for sharing!
Vince
Sent from my DROIDX using Tapatalk
Well...what do you think caused it?
To clarify my earlier statement, I don't think the pressure specification of the 5.56 is loaded to is the primary culprit. Rounds that are over pressure will pop primers. Other conditions that will pop primers are cases with over sized primer pockets, cases with under sized bases, chambers too large at the base and cases that are too soft. Any one of these conditions will allow primers to be popped more easily and any combination of these conditions will only make it worse.
To best trouble shoot what's causing popped primers, the case that popped it's primer needs to be recovered and inspected. It's also necessary to make sure the recovered case actually comes from the rifle. I know of one thread at another site that had folks scratching their heads trying to figure out how the case came to be so expanded until it was pointed out it was impossible to have come from the rifle in question
I know that's not always practical to recover the exact spent case due to conditions in training classes
MistWolf... you are absolutely correct. There were about 5k rounds of spent casings on the ground from all the firing done up to that point. It was impossible to find the exact casing that had the blown primer.
The rifle finished up the rest of the week with zero issues.
They stopped using the M193 and switched to M855.
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