So I took my Bushmaster XM-15 e2s to the range yesterday, and it jammed quite a bit. I was shooting PMC bronze ammunition, and that's what was jamming. I shot some of my friends reloads, and they shot fine. I also shot some American eagle, and it shot decent, I think I had two jams. They were FTE's and the next round was being pushed into the failures to extract round. It wasn't the magazines, I was shooting brand new PMAGS with windows. Any info on what it could've been? The rifle was well oiled and lubed.
My AR was jamming, what gives?
- Thread starter bjones870
- Start date
Slugthrower
New member
Not enough juice in the PMC loading is the likely reason. If the case is above the next round cycled off the magazine the rifle is short stroking from the bolt carrier not being forced hard enough to the rear. This would cause it to not hit the ejector hard enough, or at all, to kick the case out of the extractor pawl and to clear the ejection port. When the bolt carrier group is attempting to return to battery and the case is still held in place, or just fell on top of the magazine, it is stripping the next round off the magazine and not letting the next round feed up into the chamber properly.
Unless you mean that the round was never extracted at all and is still inside the chamber. If that is the case then you have a problem with your extractor itself. That could be several problems from a weak extractor spring, bad extractor bushing, dirty extractor pawl, or possibly even a rough chamber that is causing the extractor itself to lose it's grip on the case rim as the extraction and ejection part of the cycle is occuring.
Sometimes it is hard to diagnose a problem unless you are there to see it. ARs can have several types of malfunctions. Round over round. Double Feeds, FTEs, Stove pipes, magazines that "volcano", case head seperations, and a few others.
Not that they are common, just that they can occur in the platform from time to time. Some of which are not exclusive to the AR for that matter, even the AK can see some of those exact same problems.
Unless you mean that the round was never extracted at all and is still inside the chamber. If that is the case then you have a problem with your extractor itself. That could be several problems from a weak extractor spring, bad extractor bushing, dirty extractor pawl, or possibly even a rough chamber that is causing the extractor itself to lose it's grip on the case rim as the extraction and ejection part of the cycle is occuring.
Sometimes it is hard to diagnose a problem unless you are there to see it. ARs can have several types of malfunctions. Round over round. Double Feeds, FTEs, Stove pipes, magazines that "volcano", case head seperations, and a few others.
Not that they are common, just that they can occur in the platform from time to time. Some of which are not exclusive to the AR for that matter, even the AK can see some of those exact same problems.
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One question: What kind of jam are we talking about?
With the M16 family (to which the CAR15, M4, and numerous civvie variants belong) there are the following stoppages.
Failure to:
-Feed
-Chamber/lock
-Fire
-Unlock
-Extract/Eject
Feed is usually caused by grime in the upper reciever or crappy magazines. Most often it's bad mags.
Chamber/lock is almost always user error since it's caused by buildup of crap in the chamber or barrel extension ("star chamber"). Can also be caused by short recoil because user didn't clean his gas tube (not likely if it's a piston gun), though that usually manifests more in failure to extract/eject. BUT if your buffer spring is dirty as hell, it can provide enough resistance to not lock the bolt all the way into battery.
Fire is usually a mechanical or ammunition problem (you can tell if it's bad ammo since there's an indent on the primer. if it's just a slight indent it indicates a light primer strike which can be caused by failure to lock, or a bad sear or spring on your hammer.
Unlock. um never actually seen this one, but from what I can tell failure to unlock is caused by a ridiculously dirty weapon, specifically the barrel extension (star chamber)
extract/eject. This one can be caused by a few things. The primary suspect is grime and carbon buildup. Which makes it your fault. Clean the hell out of the bolt, and extractor. Make sure you break it all the way down and clean it with Hope's 9 before you go replace expensive parts. If it's not ejecting, it might be time to seek a stronger after market extractor.
Double Feed is caused by bad mags. Period.
cleaning tips:
Boresnake the barrel. a dozen times.
clean the hell outa your barrel extension (chamber/star chamber), don't put any sort of oil in the chamber or it'll carbonize when the first round is fired. Use dry wire brush & QTips until it's clean and shiny.
That too goes for the ring around the outside of the chamber, except feel free to lube that.
Don't be scared to break your bolt ALL THE WAY down. if you don't know how to do it, go into the gunshop and have the guy show you. I promise you he knows. It's not hard.
QTIPS & Hoppes9 are your best friends. Just be sure to dab up all the Hoppe's. a
break down the trigger group if you're comfortable doing so.... againt ehg uy at the gun shop can help you.
clean the hell outa your buffer tube and buffer spring. You'lll be surprised.
The M-16/M4 family is a deadly, reliable weapon platform, provided the user maintains said platform. If not, you might as well get a bolt .308 since it'll do more damage, and you control the cycling of the weapon.
HOPPES9 TO CLEAN, CLP to LUBE MAKES AN M4 HAPPY!
With the M16 family (to which the CAR15, M4, and numerous civvie variants belong) there are the following stoppages.
Failure to:
-Feed
-Chamber/lock
-Fire
-Unlock
-Extract/Eject
Feed is usually caused by grime in the upper reciever or crappy magazines. Most often it's bad mags.
Chamber/lock is almost always user error since it's caused by buildup of crap in the chamber or barrel extension ("star chamber"). Can also be caused by short recoil because user didn't clean his gas tube (not likely if it's a piston gun), though that usually manifests more in failure to extract/eject. BUT if your buffer spring is dirty as hell, it can provide enough resistance to not lock the bolt all the way into battery.
Fire is usually a mechanical or ammunition problem (you can tell if it's bad ammo since there's an indent on the primer. if it's just a slight indent it indicates a light primer strike which can be caused by failure to lock, or a bad sear or spring on your hammer.
Unlock. um never actually seen this one, but from what I can tell failure to unlock is caused by a ridiculously dirty weapon, specifically the barrel extension (star chamber)
extract/eject. This one can be caused by a few things. The primary suspect is grime and carbon buildup. Which makes it your fault. Clean the hell out of the bolt, and extractor. Make sure you break it all the way down and clean it with Hope's 9 before you go replace expensive parts. If it's not ejecting, it might be time to seek a stronger after market extractor.
Double Feed is caused by bad mags. Period.
cleaning tips:
Boresnake the barrel. a dozen times.
clean the hell outa your barrel extension (chamber/star chamber), don't put any sort of oil in the chamber or it'll carbonize when the first round is fired. Use dry wire brush & QTips until it's clean and shiny.
That too goes for the ring around the outside of the chamber, except feel free to lube that.
Don't be scared to break your bolt ALL THE WAY down. if you don't know how to do it, go into the gunshop and have the guy show you. I promise you he knows. It's not hard.
QTIPS & Hoppes9 are your best friends. Just be sure to dab up all the Hoppe's. a
break down the trigger group if you're comfortable doing so.... againt ehg uy at the gun shop can help you.
clean the hell outa your buffer tube and buffer spring. You'lll be surprised.
The M-16/M4 family is a deadly, reliable weapon platform, provided the user maintains said platform. If not, you might as well get a bolt .308 since it'll do more damage, and you control the cycling of the weapon.
HOPPES9 TO CLEAN, CLP to LUBE MAKES AN M4 HAPPY!
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mapsjanhere
New member
In addition to checking the extractor, give your chamber a good scrubbing. If you're playing with low end ammo you might have some coating stuck inside giving the cases just enough "stick" to make the extractor slide off the rim.
madcratebuilder
New member
PCM is weak. Your rifle is designed to work with NATO 5.56. You may need to "tune" the rifle to function with weaker ammo. You are probably short stroking. If it was an extractor it would malfunction with all ammo.
If your rifle is new try breaking it in with a few hundred rounds of nato then try the PCM again.
If your rifle is new try breaking it in with a few hundred rounds of nato then try the PCM again.
Bartholomew Roberts
Moderator
Can you clarify whether the empty case never extracted or never ejected? If it never extracted, is there a "bite" on the rim of the case or a bent rim?
My first instinct is that you need the $5 BCM extractor upgrade; but without more info, I'm just guessing.
My first instinct is that you need the $5 BCM extractor upgrade; but without more info, I'm just guessing.
The AR requires a minimum level of gas to properly function. Military ammo is loaded full power, and doesn't deviate with light loads, light bullets, or gets made to meet a price. It's all performance, and the gun is designed with that in mind.
You already figured most of it out, and the check fire with other ammo proved it. That lot of PMC doesn't work well in that AR. Don't shoot it. This happens a lot, gets posted on a lot, and it's the same thing most of the time - substandard ammo not fit to run the gun.
CCW carriers run into this with chopped .45's, and some makers exclusively recommend only one ammo, no guarantees something else won't jam right in the middle of a real gunfight. It's no different. The AR does not have a gas adjusting valve mechanism. Shoot milspec full power ammo, or put up with jams.
You already figured most of it out, and the check fire with other ammo proved it. That lot of PMC doesn't work well in that AR. Don't shoot it. This happens a lot, gets posted on a lot, and it's the same thing most of the time - substandard ammo not fit to run the gun.
CCW carriers run into this with chopped .45's, and some makers exclusively recommend only one ammo, no guarantees something else won't jam right in the middle of a real gunfight. It's no different. The AR does not have a gas adjusting valve mechanism. Shoot milspec full power ammo, or put up with jams.
Function Testing an AR is a pretty simple thing to do. You want to determine if the cause of the "jam."
The first thing to do is load a single round in a magazine, chamber it and fire it. Make sure the bolt locks back. If it doesn't you're dealing with a gas issue, buffer spring issue, or buffer weight issue. You could also have an issue with the magazine not engaging the bolt hold open as well, so I always try it with a couple of different magazines.
If it doesn't extract, then you are dealing with an extractor issue or the chamber is dirty/out of spec. If it doesn't eject, then you're dealing with an ejector issue perhaps an extractor issue.
Inspect the spent case. Make sure the rim is relatively intact. It may have a little mark where the extractor ran over the rim as it went into battery, but should not have excess pull on the case rim, or case deformation. If it does, then you've got an issue with your extractor, extractor spring.
Then you can go ahead and load 3 rounds per magazine and shoot them dry.
You have to go about things in a stepped manner in order to figure this out.
The first thing to do is load a single round in a magazine, chamber it and fire it. Make sure the bolt locks back. If it doesn't you're dealing with a gas issue, buffer spring issue, or buffer weight issue. You could also have an issue with the magazine not engaging the bolt hold open as well, so I always try it with a couple of different magazines.
If it doesn't extract, then you are dealing with an extractor issue or the chamber is dirty/out of spec. If it doesn't eject, then you're dealing with an ejector issue perhaps an extractor issue.
Inspect the spent case. Make sure the rim is relatively intact. It may have a little mark where the extractor ran over the rim as it went into battery, but should not have excess pull on the case rim, or case deformation. If it does, then you've got an issue with your extractor, extractor spring.
Then you can go ahead and load 3 rounds per magazine and shoot them dry.
You have to go about things in a stepped manner in order to figure this out.
First of all, can you clarify the failure a bit more? There is failure to extract (doesn't pull the case from the chamber) and failure to Eject (case is extracted from chamber, but not thrown clear of the gun).
It sounds like failure to eject, with the fired case being fed back towards the chamber, and jamming with the new round being srtipped from the mag. If this is what is actually happening, then your problem is most likely a bad/frozen ejector or spring. Short stroking can be an issue, but usually, if the bolt isn't going back far enough to have the fired case clear the ejection port, it isn't going back far enough to pick up a new round from the mag.
However, there is no reason these two problems cannot be happening together.
The AR bolt uses a plunger style ejector, contained in the bolt, with a spring underneath it. The statement about the bolt "hitting" the ejector is inaccurate. (it would be correct if we were talking about short stroking a Mauser or Springfield bolt action, but we aren't)
It is also possible that your extractor spring is weak, or gummed up. Check the bolt for damage to the extractor claw (unlikely if rounds are being pulled from the chamber, but not impossible), extractor movement (you should be able to push it out from the bolt face, and it should return smoothly, not stick), and ejector travel (you should be able to push it in flush with the bolt face, and it should move right back out to its "rest" position with no sticking).
If the ejector isn't moving (or sticks) then you get failure to eject. If the extractor doesn't hold the case in the bolt long enough as the bolt moves back (due to weak spring/crud/damaged hook) then the case pops loose from the bolt face, and does not eject.
These are the most likely causes of failure to eject, which is what it sounds like your rifle is doing with some ammo.
Also be aware that it could also be the fault of the ammo, and not the gun. When a gun runs fine with some ammo, but not others, it is usually the ammo, not the gun. Brass cases vary in hardness, from different makers, and sometimes even from lot to lot from the same maker.
A case that is "softer" than what the rifle is intended for will "stick" in the chamber, requiring more force to extract than a case that is "harder", which can be a cause for malfunctions. Some rifles are very picky about that, others are not so much.
There are other things which might be causing your problems, but assuming correct maint of the rifle (clean and correctly lubed) its probably the ammo.
While its nice, there is no law saying every rifle must and will shoot all ammo properly. Many will, some will not. Use what the rifle behaves with, and don't shoot what it doesn't like. If your rifle jams with brand A but works fine with Brand B, don't shoot Brand A. Simple. And if Brand B is more expensive, live with it.
It sounds like failure to eject, with the fired case being fed back towards the chamber, and jamming with the new round being srtipped from the mag. If this is what is actually happening, then your problem is most likely a bad/frozen ejector or spring. Short stroking can be an issue, but usually, if the bolt isn't going back far enough to have the fired case clear the ejection port, it isn't going back far enough to pick up a new round from the mag.
However, there is no reason these two problems cannot be happening together.
The AR bolt uses a plunger style ejector, contained in the bolt, with a spring underneath it. The statement about the bolt "hitting" the ejector is inaccurate. (it would be correct if we were talking about short stroking a Mauser or Springfield bolt action, but we aren't)
It is also possible that your extractor spring is weak, or gummed up. Check the bolt for damage to the extractor claw (unlikely if rounds are being pulled from the chamber, but not impossible), extractor movement (you should be able to push it out from the bolt face, and it should return smoothly, not stick), and ejector travel (you should be able to push it in flush with the bolt face, and it should move right back out to its "rest" position with no sticking).
If the ejector isn't moving (or sticks) then you get failure to eject. If the extractor doesn't hold the case in the bolt long enough as the bolt moves back (due to weak spring/crud/damaged hook) then the case pops loose from the bolt face, and does not eject.
These are the most likely causes of failure to eject, which is what it sounds like your rifle is doing with some ammo.
Also be aware that it could also be the fault of the ammo, and not the gun. When a gun runs fine with some ammo, but not others, it is usually the ammo, not the gun. Brass cases vary in hardness, from different makers, and sometimes even from lot to lot from the same maker.
A case that is "softer" than what the rifle is intended for will "stick" in the chamber, requiring more force to extract than a case that is "harder", which can be a cause for malfunctions. Some rifles are very picky about that, others are not so much.
There are other things which might be causing your problems, but assuming correct maint of the rifle (clean and correctly lubed) its probably the ammo.
While its nice, there is no law saying every rifle must and will shoot all ammo properly. Many will, some will not. Use what the rifle behaves with, and don't shoot what it doesn't like. If your rifle jams with brand A but works fine with Brand B, don't shoot Brand A. Simple. And if Brand B is more expensive, live with it.
sigshepardo
New member
my guess is the rounds were bad. Maby too long for the chamber? I had a similar issue with a Rock River .458 SOCOM
Three rounds of AE through my new rifle
Ok. Here is what I had happen today. Searched and found this thread before posting my own and figured that I could elaborate on the extraction problem. Brought home my new AR today and test fired a couple rounds only to experience an extraction issue on the first round.
Fired my first round and put the rifle on safe. Passed it to my wife to shoot a round but when she pulled the trigger, nothing. Upon inspecting the rifle, noted that the round failed to extract and in turn, failed to feed the next round (first pic is of the feed failure round).
Cleared the jam. Charged the rifle three times and the spent casing finally ejected (second pic is the first extraction failure with the feed failure). Reloaded the rifle and the wife shot once. We are planning on going shooting this weekend so shooting these rounds in the back yard (alarming all neighborhood dogs) had already accomplished the days mission. Put it back on safe, dropped the mag, ejected the round from the chamber (no problem here) and laid the rifle down.
At this point I turned to inspecting the spent cases. The case that had the failure to extract had torn the rim all the way off during extraction. The other spent case had a noticeable rip on the rim from extraction. I then took a magazine with a single round back outside, charged, fired, and the bolt locked to the rear with no failure to extract. Picked up the case to find another rip from the extraction.
All three spent casings are scuffed all along the casing except for roughly a quarter inch up from the rim. The cases appear to have swelled up when shot causing them to stick in the chamber and creating the extraction problem. Cycled two other rounds through the without firing and there are no scuffing or extraction issues.
Ok. Here is what I had happen today. Searched and found this thread before posting my own and figured that I could elaborate on the extraction problem. Brought home my new AR today and test fired a couple rounds only to experience an extraction issue on the first round.
Fired my first round and put the rifle on safe. Passed it to my wife to shoot a round but when she pulled the trigger, nothing. Upon inspecting the rifle, noted that the round failed to extract and in turn, failed to feed the next round (first pic is of the feed failure round).
Cleared the jam. Charged the rifle three times and the spent casing finally ejected (second pic is the first extraction failure with the feed failure). Reloaded the rifle and the wife shot once. We are planning on going shooting this weekend so shooting these rounds in the back yard (alarming all neighborhood dogs) had already accomplished the days mission. Put it back on safe, dropped the mag, ejected the round from the chamber (no problem here) and laid the rifle down.
At this point I turned to inspecting the spent cases. The case that had the failure to extract had torn the rim all the way off during extraction. The other spent case had a noticeable rip on the rim from extraction. I then took a magazine with a single round back outside, charged, fired, and the bolt locked to the rear with no failure to extract. Picked up the case to find another rip from the extraction.
All three spent casings are scuffed all along the casing except for roughly a quarter inch up from the rim. The cases appear to have swelled up when shot causing them to stick in the chamber and creating the extraction problem. Cycled two other rounds through the without firing and there are no scuffing or extraction issues.
Fire the AE stuff all the time in my three AR-15s and have never seen that. The only problem I had was with my DoubleStar AR-15 when it was new. A extractor spring kit from Brownells fixed my problem. I would have bought it from BCM but they were out. When I repalced the spring and O ring I noticed a difference in the extractor as it appeared to be pulled in tighter towards the bolt face than the original spring set did before I changed it out. Looking at those photos it appears as if the whole extractor is not getting a full grip on the case rim.
As you say the cases are scuffed lengthwise too. Might want to take some pics in good light and e-mail the mfg with them.
As you say the cases are scuffed lengthwise too. Might want to take some pics in good light and e-mail the mfg with them.
Bartholomew Roberts
Moderator
Dcobler, It looks like your AR is starting extraction while the brass is still expanded against the chamber wall. It looks like your extractor is getting a good bite on the rim, so that looks OK.
The first thing I would try is different ammo or even a different lot of American Eagle. Normally that is decent ammo; but it wouldn't be the first bad lot Federal put out. If it works OK with other ammo, that may help narrow the problem down.
If you see the same problem with other brass cased ammo, the next thing I'd try is a heavier buffer.
The first thing I would try is different ammo or even a different lot of American Eagle. Normally that is decent ammo; but it wouldn't be the first bad lot Federal put out. If it works OK with other ammo, that may help narrow the problem down.
If you see the same problem with other brass cased ammo, the next thing I'd try is a heavier buffer.
tears on, or through the rim from the extractor mean a timing issue. The bolt it trying to open and extract the case before the pressure has dropped enough for the case to release its grip on the chamber walls.
Now while the relative hardness or softness of the brass can affect this issue, it is usually a matter of the gas system, combined with the powder used.
it was this issue that got a bunch of our soldiers hurt and killed in Vietnam. Changes in the specs of the GI ammo (powder/buring rate-pressure curve) caused large numbers of jams back then.
What seems most likely is that the specific batch of ammo you have is borderline for your rifle. This is supported by the fact that other ammo works better, or properly in your rifle.
Proper function of a gas operated semi auto is a balancing act between the mechanics of the rifle and the pressure curve of the ammo used. While most ammo is good enough for most rifles, one sometimes gets a combination that just doesn't suit.
Get some differnt ammo, and see how it works.
Now while the relative hardness or softness of the brass can affect this issue, it is usually a matter of the gas system, combined with the powder used.
it was this issue that got a bunch of our soldiers hurt and killed in Vietnam. Changes in the specs of the GI ammo (powder/buring rate-pressure curve) caused large numbers of jams back then.
What seems most likely is that the specific batch of ammo you have is borderline for your rifle. This is supported by the fact that other ammo works better, or properly in your rifle.
Proper function of a gas operated semi auto is a balancing act between the mechanics of the rifle and the pressure curve of the ammo used. While most ammo is good enough for most rifles, one sometimes gets a combination that just doesn't suit.
Get some differnt ammo, and see how it works.
I was wondering if I had a chamber problem and intend to try and polish it up a bit and was going to run some different ammo as well. Timing does also stand as a serious possibility but as the possibilty that I am hoping against. Going to pick up some different ammo today and I will keep the correction attempts and tests separate to identify the exact problem. Thank you to everyone for your ideas and I will keep you posted on what I find or don't find.
I also called Federal and left a message since there has been a similar case as listed in this post originally.
I also called Federal and left a message since there has been a similar case as listed in this post originally.
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