View Full Version : What is this type of failure attributed to?
Had this happen on Saturday.
-Ammo used was Independence 55gr fmj.
-Rifle Colt 6920. Completely stock.
-mag was a new Troy Battle mag
-Weather was sunny and breezy
Loaded 3 rounds in the mag. Chambered 1st round and shot. Upon upon extraction the case goes up and above the bolt (see pic). Remove mag, clear the malfunction, insert the mag back in with the remaining 2 rounds and shoot without incident.
Same mag, next 3 rounds same problem. Clear, insert the mag back in with the remaining 2 rounds and shoot without incident.
Repeat again twice, this time without issue.
Repeat again same thing happened. 1st round jammed up above the bolt. Clear and shoot the remaining 2 rounds without issue.
Took out a different mag. A no name gray aluminum used mag. Repeat the same 3 shot with the same ammo for the next 40 rounds without issue.
http://uploads.tapatalk-cdn.com/20161107/2c6e42b2251b4f86636f74269f6c46aa.jpg
This is not my picture. Just something I found online to show example of.
The only thing I changed was the mag. Could a mag cause this malfunction?
I've had this rifle at a few classes, in different weather, using Wolf Gold and Pmags without issues.
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Bent/crappy feed lips on magazine perhaps
Mag issue. The round is popping up out of the mag as the BCG is coming forward.
Take the mag, load 5-10 rounds into it and slap the bottom. Odd are you will get a show
So the next round is popping up and pushing the empty case up as the bolt comes forward?
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So you are getting an empty case stuck? The picture shows a live roud.
So you are getting an empty case stuck? The picture shows a live roud.
Correct, empty case. The pic is just something I downloaded to show how it's getting stuck. More like this.
Fixed the original pic
http://uploads.tapatalk-cdn.com/20161107/0ff4c9e0f8326a5e73320e470da5c35f.jpg
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556BlackRifle
11-07-16, 09:29
Could be a combination of weak extraction and short stroking. As mentioned try a new mag but also check your bolt for proper extractor tension and check the gas system. Rings, carrier key, gas tube, gas block, etc. Good luck and let us know what you find.
eightmillimeter
11-07-16, 10:48
By far my experience with this type of malfunction was with live rounds and was a magazine issue each time.
With empties I'd highly suspect something with an ejector/extractor, along with a possible under gassed scenario.
Wouldn't under gassed/extractor/ejector cause this problem all the time....or rather not just on the 1st round? In other words, wouldn't it be consistent? After trying a different mag the problem went away
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This happened to me once. It's mainly a magazine issue
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What if you load 30 rounds? Does the first round cause it and not the next 29?
Wouldn't under gassed/extractor/ejector cause this problem all the time....or rather not just on the 1st round? In other words, wouldn't it be consistent? After trying a different mag the problem went away
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If the gun is undergassed / too heavy a buffer, etc. the extra spring pressure exerting from the magazine could be slowing the action enough to (when combined with a weak EJECTOR..and perhaps extractor) cause the malfuction. I would see if 4 or 5 rounds loaded in the mag causes it on more than the first round. (More rounds in mag = more pressure exerted against the bottom of the bolt carrier).
What if you load 30 rounds? Does the first round cause it and not the next 29?
I'll try next week. This range only allowed 3 rounds at a time from a rifle (state game land)
If the gun is undergassed / too heavy a buffer, etc. the extra spring pressure exerting from the magazine could be slowing the action enough to (when combined with a weak EJECTOR..and perhaps extractor) cause the malfuction. I would see if 4 or 5 rounds loaded in the mag causes it on more than the first round. (More rounds in mag = more pressure exerted against the bottom of the bolt carrier).
Last time I ran this rifle it was a few months ago at a class. Put something like 350 - 400 rounds without issue. All mags (Pmags) were loaded to capacity and no failures. Ammo used was 55gr Wolf Gold
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Short stroking combined with extraction issues.
If it were the mag, the empty case would eject and a live round would be the problem. The carrier holds the top round in the mag down until after the empty has cleared the ejection port.
If it was only short stroking, the extractor would still be controlling the empty.
If it was simply an extraction or ejection problem, the bolt would be attempting to strip the next round from the mag.
Try placing a single round in the mag, load it in the rifle and fire it. See if the carrier locks back or if the problem happens again
I keep going back to a mag issue
Short stroking combined with extraction issues.
If it were the mag, the empty case would eject and a live round would be the problem. The carrier holds the top round in the mag down until after the empty has cleared the ejection port.
If it was only short stroking, the extractor would still be controlling the empty.
If it was simply an extraction or ejection problem, the bolt would be attempting to strip the next round from the mag.
Try placing a single round in the mag, load it in the rifle and fire it. See if the carrier locks back or if the problem happens again
It did lock back each time when at the range. Assuming the range won't be a hectic mess this upcoming weekend I'll try one round at a time. I'll also bring several other mags and another AR
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Independence Ammo is crap. I wouldn't shoot it in anything I value.
Independence Ammo is crap. I wouldn't shoot it in anything I value.
Thanks for the heads up. I bought 5 a while ago to try and just got around to remembering I had them. Isn't it IMI rebranded?
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Thanks for the heads up. I bought 5 a while ago to try and just got around to remembering I had them. Isn't it IMI rebranded?
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Negative. IMI M193 would be a beter choice than Independence.
Thanks for the heads up. I bought 5 a while ago to try and just got around to remembering I had them. Isn't it IMI rebranded?
IMI loaded it using ATK/Lake City components. They loaded ammo for the US Army under contract the same way during the Iraq surge when the US was scrambling for alternate production lines.
https://farm4.staticflickr.com/3734/11111911743_469b98e524_o.jpg
According to what I was told that ammo is loaded for Federal to their specs at a separate place that has nothing to do with IMI. There are multiple threads here on M4C about this ammo causing issues.
IMI loaded it using ATK/Lake City components. They loaded ammo for the US Army under contract the same way during the Iraq surge when the US was scrambling for alternate production lines.
https://farm4.staticflickr.com/3734/11111911743_469b98e524_o.jpg
http://www.rense.com/general67/bullets.htm
You can buy different lots of Independence M193 equivalent and it'll have either FC (Federal Cartridge components, possibly from Winoka, Minnesota) or LC (Lake City) headstamped cases.
Independence is VERY flashy and tends to run VERY hot-fast. The ammo I've shot (from M4s, M16s, mids, and Mark 46 SAWs) has occasionally spewed out primers.
Sorry for the thread drift.
Some updates.
Finally got a day off. Went to the range with different mags and ammo.
The rifle was left as it was, no cleaning, no nothing. Brought PPU white box.....I guess its surplus ammo. Hungarian MVS or whatever, AE black box and the Independence. All 55gr. Also brought 3 mags. The Troy that was giving me problems, Pmag and and old Colt aluminum mag.
Started with Independence, loaded the same way as before, 3 rounds in 3 mags. All shot fine. Did different amounts. Loaded 3, 7, 10, 20, 30, 15...etc. all were fine except the same Troy mag with the same ammo had a stoppage 10 rounds into a 15 round mag.
http://uploads.tapatalk-cdn.com/20161210/12ac285e0ba8ce31eeff7841368750b3.jpg
After that I went through all the other ammo in all 3 mags without issue. Only thing I can think of is something about that mag and that amount just doesn't work
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How old is the Troy mag? I have a few from some time ago and have noticed that the feed lips have spread.
How old is the Troy mag? I have a few from some time ago and have noticed that the feed lips have spread.
New. Maybe 6 months
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