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Posted: 11/18/2009 7:52:05 PM EDT
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Hi, I've been going through a good number of pages here and I'm not seeing anything on this, but please let me know if this has been covered in some way already.
I bought a new Bushmaster AR15 M4 type a couple of months ago, and have put about 400 rounds of wolf .223 through it without any issues. It's been extremely reliable and accurate enough for the 25 yard indoor range I usually take it too. About 2 weeks ago, I started getting huge failure to feed issues. It wouldn't pick up rounds from the magazine, it would fire one round, and I'd have to manually cycle the charging handle for it to feed another one, sometimes it grabs a round but the bolt only closes halfway and the round gets slammed into the chamber ramp, between the teeth. The gun is for the most part unusable at this point. When I had the gun store guy at the range the other day, we fired some PMC FMJ through it and it all worked fine, followed by more Wolf which also seems to go well. We chalked it up to a bad box of ammo that I had kept retrying. Today, it started happening again with any box of wolf I tried (I've got 600 rounds of the stuff at this point) where it won't fire more than 1 round at a time, and I tried some of my friend's hand loaded brass cased .223. No go with that either. Same feed issues. I took a big amount of the ammo that was having the most problems and put it through his M4, it fired everything with zero issues. We even tried his lower on my upper, same issues... Anyone run into this? The gun store guys and my friend have looked at all the innards, the bolt carrier group, the chamber ramp, nothing is sheered off and everything looks great. It's clean as a whistle at this point as well. I'm stumped. Here are some pics, sorry for the poor cell phone quality. http://militaryphotos.net/forums/picture.php?albumid=1333&pictureid=18137 http://militaryphotos.net/forums/picture.php?albumid=1333&pictureid=18136 |
| Hi, yes and yes. I was using some plastic dpms mags, and I've switched to 30 round pre-ban metal ones. Same thing happens with the 10 rounder metal mag that came with the rifle. When I cleaned it recently after all of this started happening, I did quite a bit with a metal chamber brush and have scrubbed it to spotlessness with a toothbrush with some solvent on it. |
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Hi, some better pics of the bolt teeth and chamber ramps below. Concerning the mag test you mentioned, if I put an empty mag in, it indeeds locks the bolt in the rear position if I cycle the charging handle. If there's a round in there, it chambers the round. I can seem to cycle rounds manually without a problem. They go popping out in short order. Firing one and having to manually cycle would probably point to lack of enough gas pressure to cycle it properly on it's own. The misfeeds however seem to point to something else which is stumping me.
http://militaryphotos.net/forums/picture.php?albumid=1333&pictureid=18139 http://militaryphotos.net/forums/picture.php?albumid=1333&pictureid=18138 |
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In that last picture it looks like the M4 feed ramps don't line up exactly, it looks rotated counter clockwise or like the right one is shifted right.
I have something else I need you to do. 1) take out the BCG and pull the bolt out as far as it will go. Stand the BCG with the bolt extended up on end (bolt face down). Does the bolt collapse back into the carrier? 2) now manually retract the bolt into the carrier, just push it in with your hand. Take the whole BCG in your dominant hand and swing it from your head to your feet. Attempt to use centrifugal force to extend the bolt out of the BCG. Can you force it to extend with a reasonable ammount of force? 3) remove the firing pin retaining cotter pin, remove the firing pin, remove the cam pin and remove the bolt from the BCG. does the extractor appear to be flush with the surface of the bolt? Do you see any contact markings? 4) Do you see any contact marks on the BCG from it dragging in the receiver anywhere? 5) Try your friends BCG in your upper with your lower. If that works, try his bolt in your BCG, if that works replace your bolt and or BCG. If you get this far I wouldn't risk his carrier with a possibly bad bolt. Consider replacing your whole BCG with a BCM or LMT set. Let us know, and good luck. |
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Can't tell from the pics of the assembled rifle, but the bare bolt and carrier look dry.
Did you lube it after you cleaned it? You sholud be able to see a film of oil on the bolt and carrier. Oil the gas rings and bolt body before putting it in the carrier. A few drops of oil down the carrier key too. There's quite a bit of carbon on that gas tube too. Check your carrier key isn't blocked. Pull the bolt and post a pic. What buffer are you running? |
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Can't tell from the pics of the assembled rifle, but the bare bolt and carrier look dry. Did you lube it after you cleaned it? You sholud be able to see a film of oil on the bolt and carrier. Oil the gas rings and bolt body before putting it in the carrier. A few drops of oil down the carrier key too. There's quite a bit of carbon on that gas tube too. Check your carrier key isn't blocked. Pull the bolt and post a pic. What buffer are you running? Indeed, it looks like it could use some better cleaning and a lube. I wonder if the gas key isn't jamming over the tube... He said it was happening on another lower, makes me lean away from a buffer/spring issue on first thought. |
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Can't tell from the pics of the assembled rifle, but the bare bolt and carrier look dry. Did you lube it after you cleaned it? You sholud be able to see a film of oil on the bolt and carrier. Oil the gas rings and bolt body before putting it in the carrier. A few drops of oil down the carrier key too. There's quite a bit of carbon on that gas tube too. Check your carrier key isn't blocked. Pull the bolt and post a pic. What buffer are you running? Indeed, it looks like it could use some better cleaning and a lube. I wonder if the gas key isn't jamming over the tube... He said it was happening on another lower, makes me lean away from a buffer/spring issue on first thought. Yes you're right. Forgot about the lower swap. |
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Oh, so load one round, cycle the handle so it chambers it, fire it, and see if it holds the bolt back with the empty mag? Sounds like a good idea. I'll try it tomorrow. Thanks. Thanks for all of the replies guys, I grabbed some more PMC FMJ rounds and I took 1 round out of each of the 20+ boxes of wolf 55 gr hp that I bought in bulk (argh) and went to the range tonight. I did the test where I put 1 round of the wolf in the mag and fired it. I did this for 10 of the rounds. Every single one didn't hold the bolt back on the now empty mag. I put 3 rounds in of the wolf next, so there would be one loading from each side in case there was a feed ramp issue. Same exact thing. I had to manually cycle each round for it to chamber them. No holding back of the bolt. I then loaded up the PMC FMJ rounds. Every single one fired flawlessly. Bolt held back on the 1 round per mag test, with 10 tests. I then filled up the rest of the mag with what I had left and fired them all off. No problems, no manual cycling required. When I got home and had a look at the feed ramps, it looks like it's just a picture angle issue with what I posted, so that rules out the possible feed ramp line-up issue that someone here mentioned. Given this set of events, is my gun just not able to deal with wolf anymore and I should try a different brand, or should I continue to run through the various ideas mentioned above because something broke or has become defective? I had cleaned and lubed everything up, and fired about 50 rounds through it before taking the original pictures, so that's probably why it looked less than pristine. It exhibited the same behavior even when glistening with lube. http://militaryphotos.net/forums/picture.php?albumid=1333&pictureid=18145 |
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Just off the blurry pics you present. It looks like something I had an issue with on my first Bushy.
I quite simply replaced the extractor and spring. If the extractor looses grip on the rim of the spent cartridge it may seem to be a short stroke. Extractors wear......replace them. 
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Just off the blurry pics you present. It looks like something I had an issue with on my first Bushy. I quite simply replaced the extractor and spring. If the extractor looses grip on the rim of the spent cartridge it may seem to be a short stroke. Extractors wear......replace them. One of the guys at the gun store mentioned that he did this for his AR15 since he uses all steel case ammo. Sounds like I'll be taking him up on his offer to do the same for me. Thanks. |
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Just off the blurry pics you present. It looks like something I had an issue with on my first Bushy. I quite simply replaced the extractor and spring. If the extractor looses grip on the rim of the spent cartridge it may seem to be a short stroke. Extractors wear......replace them. These are awesome extractor kits. I put them in all of mine. Good Luck.
http://www.bravocompanyusa.com/BCM-Extractor-Spring-Uprade-Kit-p/bcm%20extractor%20spring%20upgrade.htm |
| I receintly had the same problem with my new upper. I read all the posts, and tried all options includding mags & ammo. The last thing i did was make it"wet". I dipped the whole BCG in Formula 3 gun conditioner. Dripping Wet. Did a quick drip dry, no wipe down, and BAM, BAM. I'm lucky to walk out my back door to test fire. PS. I now have 2 ar rifles and they both shoot Wolf and Brown Bear with no problems since and I shoot 100-200 rounds a week at home. Good luck. |
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I receintly had the same problem with my new upper. I read all the posts, and tried all options includding mags & ammo. The last thing i did was make it"wet". I dipped the whole BCG in Formula 3 gun conditioner. Dripping Wet. Did a quick drip dry, no wipe down, and BAM, BAM. I'm lucky to walk out my back door to test fire. PS. I now have 2 ar rifles and they both shoot Wolf and Brown Bear with no problems since and I shoot 100-200 rounds a week at home. Good luck. I run all my ARs wet. If you can't spread the oil with your finger it's not heavy enough. I have four 5.56 rifles from three different manufacturers. All run flawlessly with Wolf 55, 62 and 75. Wolf is underpowered. Just that little bit of friction from a dry spot coupled with a dirty chamber (from the dirty ammo) and underpowered ammo can cause malfuntions. Your new ammo comparison gives an indication to this as a possible cause. The ammo isn't pushing the bolt far enough back during cycling. Short stroking. But it doesn't sound like a gas system problem, because the PMC worked fine. And your friend's rifle functioned OK with the Wolf. His rifle may be better lubed or have a few looser tolerances. I mostly follow Quib's lube advice. Put a drop of oil on the charging handle bearing "nubs" on top. Put a drop of oil on the extractor pivot/pin. Put several drops of oil on the gas rings, several on the forward bearing ring on the bolt that rides inside the carrier. Put a couple of drops on the bolt lugs. Put a couple of drops on the cam pin, a couple more inside the cam pin hole. Put a drop of oil on the firing pin. Put several drops of oil on the four bolt carrier rails. Put a couple drops of oil down the carrier key. Then hand cylce it 5-10 times after reassmbly to distribute the oil. That takes about 1/10th the time to do as it does to read. I don't want to start a huge debate about lube products, but I use full synthetic mutli-grade motor oil on all my ARs. I shoot at least one of them weekly or bi-weekly. I've never had a failure that wasn't traceable to something else, like a misaligned 9mm ejector. |
lube always helps but these things aren't supposed to run only under ideal conditions, they are meant to be submerged and surrounded by water and sand and mud and be fired for days of combat without a full cleaning and with minimal to no service through hundreds of rounds. 
I would like to hear the results of what I suggested above just to make sure everything is moving like it should inside. I may just be paranoid as I just went through similiar issues that actually had a manufacturing defect as the cause. |
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lube always helps but these things aren't supposed to run only under ideal conditions, they are meant to be submerged and surrounded by water and sand and mud and be fired for days of combat without a full cleaning and with minimal to no service through hundreds of rounds.
I would like to hear the results of what I suggested above just to make sure everything is moving like it should inside. I may just be paranoid as I just went through similiar issues that actually had a manufacturing defect as the cause. I'm with you on this, and it only started happening after 3-400 rounds of wolf, so I'd like to think it's just something like lack of lube or a worn spring that's the cause. I'm able to get back to the range in a few days, so I'm going to take a crack at all of these things over the weekend in preparation for it. |
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What is interesting about your situation is the fact 400 or so rounds cycled ok before the problem started. Might try cleaning out the buffer spring tube and spraying it down with Hornaday Dry Lube. Just grabbing at straws here. Three months ago I obtained a new Bushmaster which is my first venture into ar15/.223 activity. Until my dies and other stuff pretaining to loading .223 arrived I bought some loaded ammo so I could at least shot the rifle.
I purchased a box of Hornaday .223 and a few boxes of Wolf ammo. The rifle would not fully cycle either brand. Would not come quite far enough back to pick up a fresh round. Started lading and as long as I kept the pressure up with medium to slow powders (H-335, H 4895, A2230, A2520, Varget, BL-C(2), etc) the rifle works just great. I also lube the bolt and carrier with One Shot grease (-65 to 350 F). I live in Alaska nd will do my weekly target shooting at the outdoor range tomorrow morning. The temp will be 20 below F. No place for grease or other lubes which are not cold tolerent. ps-Don know how the military kept therir guns working during the winter "Siege of Moscow". Hope some of this might be helpful
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So as to add closure to this thread, I sent off the rifle to Bushmaster with the help of my most excellent local gun store, and got it back with a page with the below on it (see pic). Apparently some of the gas rings were broken and there was something wrong with the gas key, although the second looked fine to visual inspection. That said, by the time I brought it into the gun store, the BCG wasn't staying in by itself anymore. If I had the upper separated from the lower, and I tilted the upper back, gravity would pull out the BCG by itself, which is not supposed to happen without a little pulling on it.
http://militaryphotos.net/forums/picture.php?albumid=1333&pictureid=19380 |
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