gerritm Posted January 2, 2012 Share Posted January 2, 2012 (edited) Maybe someone can give me an idea what is happening with these rounds jamming in my son's .223 AR carbine. It is an Olympic lower and we are not sure what the upper is. The barrel is stamped .556. these jams happen randomly, no obvious pattern. Gun is new, 500 rounds thru it, only change is a 1" longer DPMS adjustable stock. Reused the buffer and spring. Gun functions 99%. We shoot only brass cased PMC, Lake City, or Federal. We have shot .556 LC and it seems to happen more often with the .556 than the .223. It has happened with different mags. We use Magpul 30 round P mags. Seems like a double feed where the bottom shell deforms or bends and if it makes it into the chamber it jams. Once into the chamber we have to pound the stock on the ground or remove it with a knife blade. Has happened on the first shell or into the mag at random amounts fired. Seems like if you download the mag to 28 it is less frequent, but only happens once every 100 rounds or so. Any ideas or help would be appreciated. gerritm Edited January 2, 2012 by gerritm Link to comment Share on other sites More sharing options...
3gungeezer Posted January 2, 2012 Share Posted January 2, 2012 Could you be more specific about what is happening? Are you having failures to go into battery and the round when removed looks like this? Are you having double feeds? Your description of the problem is a little vague. Do the feed ramps on the barrel and upper match up? Does the barrel possibly not have M4 ramps and your lower does. this can cause the bullet tip to catch and deform the round. Give us more information please Geezer Link to comment Share on other sites More sharing options...
Alaskapopo Posted January 2, 2012 Share Posted January 2, 2012 Maybe someone can give me an idea what is happening with these rounds jamming in my son's .223 AR carbine. It is an Olympic lower and we are not sure what the upper is. The barrel is stamped .556. these jams happen randomly, no obvious patter. Gun is new, 500 rounds thru it, only change is a 1" longer DPMS adjustable stock. Reused the buffer and spring. Gun functions 99%. We shoot only brass cased PMC, Lake City, or Federal. We have shot .556 LC and it seems to happen more often with the .556 than the .223. It has happened with different mags. We use Magpul 30 round P mags. Seems like a double feed where the bottom shell deforms or bends and if it makes it into the chamber it jams. Once into the chamber we have to pound the stock on the ground or remove it with a knife blade. Has happened on the first shell or into the mag at random amounts fired. Seems like if you download the mag to 28 it is less frequent, but only happens once every 100 rounds or so. Any ideas or help would be appreciated. gerritm If its the first round fed and looking at the dent on the bullet that looks like you are overloading the mag causing the round to be deformed by the bottom of the bolt when you insert the mag. Are you counting how many rounds you are putting in the mag. Some older PMags will hold 31 rounds but will not work right with 31 rounds. Pat Link to comment Share on other sites More sharing options...
gerritm Posted January 2, 2012 Author Share Posted January 2, 2012 Sorry, not trying to be vague. Today it happened going into battery, Never got the first shot off. But it has happened in the middle of a mag. The bent shell came out of the chamber by prying and the shell below it came out of the mag and fed up against it and jammed like a double feed. It is very random. Shot 100 rounds between issues. Then it may happen a couple of times. We have no history on who built the rifle. My son won it. I checked the Olympic Arms website and there is no rifle like this. It is a flat top with a 16" M4 type barrel and standard military type flash hider that we have changed to a Miculek comp. Shoots well, good accuracy out to 500 yards. The lower says Olympic Arms Cal. multi 2011 mod m.f.r. Nothing else on the upper or lower. Barrel is stamped .556. We are going to remove the barrel tomorrow. How can I check to see if the feed ramp on the barrel and the lower match. I thought there was an alignment pin to position the barrel. How can I check to see if the barrel does not have M4 ramp and the lower does. thanks, gerritm Link to comment Share on other sites More sharing options...
fueddy Posted January 2, 2012 Share Posted January 2, 2012 If the problem is happening with 556 ammo only then I'd think that your problem is the chamber of this bbl. I have a crazy tight chamber in my cmmg from when they chromed the chamber/bbl. I wonder if you have something as well. To resize I have to use a hand press to make sure the resize die gets all the way down the brass unlike my progressive press lol Hows the bolt feel going in the chamber? Unfinished chamber? Seen it a few times on some factory guns. Link to comment Share on other sites More sharing options...
Alaskapopo Posted January 2, 2012 Share Posted January 2, 2012 Sorry, not trying to be vague. Today it happened going into battery, Never got the first shot off. But it has happened in the middle of a mag. The bent shell came out of the chamber by prying and the shell below it came out of the mag and fed up against it and jammed like a double feed. It is very random. Shot 100 rounds between issues. Then it may happen a couple of times. We have no history on who built the rifle. My son won it. I checked the Olympic Arms website and there is no rifle like this. It is a flat top with a 16" M4 type barrel and standard military type flash hider that we have changed to a Miculek comp. Shoots well, good accuracy out to 500 yards. The lower says Olympic Arms Cal. multi 2011 mod m.f.r. Nothing else on the upper or lower. Barrel is stamped .556. We are going to remove the barrel tomorrow. How can I check to see if the feed ramp on the barrel and the lower match. I thought there was an alignment pin to position the barrel. How can I check to see if the barrel does not have M4 ramp and the lower does. thanks, gerritm Oh its an Oly that is your problem. Hated the one I used to own and it was nothing but trouble. Dump it. Pat Link to comment Share on other sites More sharing options...
gerritm Posted January 2, 2012 Author Share Posted January 2, 2012 Maybe someone can give me an idea what is happening with these rounds jamming in my son's .223 AR carbine. It is an Olympic lower and we are not sure what the upper is. The barrel is stamped .556. these jams happen randomly, no obvious patter. Gun is new, 500 rounds thru it, only change is a 1" longer DPMS adjustable stock. Reused the buffer and spring. Gun functions 99%. We shoot only brass cased PMC, Lake City, or Federal. We have shot .556 LC and it seems to happen more often with the .556 than the .223. It has happened with different mags. We use Magpul 30 round P mags. Seems like a double feed where the bottom shell deforms or bends and if it makes it into the chamber it jams. Once into the chamber we have to pound the stock on the ground or remove it with a knife blade. Has happened on the first shell or into the mag at random amounts fired. Seems like if you download the mag to 28 it is less frequent, but only happens once every 100 rounds or so. Any ideas or help would be appreciated. gerritm If its the first round fed and looking at the dent on the bullet that looks like you are overloading the mag causing the round to be deformed by the bottom of the bolt when you insert the mag. Are you counting how many rounds you are putting in the mag. Some older PMags will hold 31 rounds but will not work right with 31 rounds. Pat No, we always count and download to 28 at matches. Wish it was that easy. He shot about 150 rounds between it happening out of different mags sometimes with only 5 or 6 in the mag at the range. It has happened with that few in the mag. Link to comment Share on other sites More sharing options...
gerritm Posted January 2, 2012 Author Share Posted January 2, 2012 If the problem is happening with 556 ammo only then I'd think that your problem is the chamber of this bbl. I have a crazy tight chamber in my cmmg from when they chromed the chamber/bbl. I wonder if you have something as well. To resize I have to use a hand press to make sure the resize die gets all the way down the brass unlike my progressive press lol Hows the bolt feel going in the chamber? Unfinished chamber? Seen it a few times on some factory guns. That is what we originally thought that it was the .556 ammo. Switched to .223 ammo and shot about 150 rounds at the range and figured it was the problem. At the match yesterday it happened with .223 ammo. All factory ammo. .556 was Lake City and Federal. .223 was PMC. Barrel is marked .556. Could there be a burr or rough spot on the feed ramp that certain rounds maybe slighty longer is catching on? Any ways we are going to take the barrel off today and look. Bolt seems to go into the chamber smoothly. Link to comment Share on other sites More sharing options...
gerritm Posted January 2, 2012 Author Share Posted January 2, 2012 Sorry, not trying to be vague. Today it happened going into battery, Never got the first shot off. But it has happened in the middle of a mag. The bent shell came out of the chamber by prying and the shell below it came out of the mag and fed up against it and jammed like a double feed. It is very random. Shot 100 rounds between issues. Then it may happen a couple of times. We have no history on who built the rifle. My son won it. I checked the Olympic Arms website and there is no rifle like this. It is a flat top with a 16" M4 type barrel and standard military type flash hider that we have changed to a Miculek comp. Shoots well, good accuracy out to 500 yards. The lower says Olympic Arms Cal. multi 2011 mod m.f.r. Nothing else on the upper or lower. Barrel is stamped .556. We are going to remove the barrel tomorrow. How can I check to see if the feed ramp on the barrel and the lower match. I thought there was an alignment pin to position the barrel. How can I check to see if the barrel does not have M4 ramp and the lower does. thanks, gerritm Oh its an Oly that is your problem. Hated the one I used to own and it was nothing but trouble. Dump it. Pat Yea I know the reputation of Oly, but he won the rifle and it actually does shoot very well. We regularily shoot out to 300-500 yards at one match it is very accurate for an inexpensive 16" carbine rifle. My feeling is someone put this rifle together for the raffle with parts left over. He really likes it and I hate to sell it and give someone else a headache. gerritm Link to comment Share on other sites More sharing options...
GentlemanJim Posted January 2, 2012 Share Posted January 2, 2012 Check that your barrel extension and upper are both compatible You cant have an a4 upper and an a2 extension Jim Link to comment Share on other sites More sharing options...
gerritm Posted January 2, 2012 Author Share Posted January 2, 2012 Check that your barrel extension and upper are both compatible You cant have an a4 upper and an a2 extension Jim When you say A2 extension. Do you mean the buffer tube? We did change out the stock including the tube but not the spring and buffer. gerritm Link to comment Share on other sites More sharing options...
Shooter115 Posted January 2, 2012 Share Posted January 2, 2012 (edited) Check that your barrel extension and upper are both compatible You cant have an a4 upper and an a2 extension Jim When you say A2 extension. Do you mean the buffer tube? We did change out the stock including the tube but not the spring and buffer. gerritm He's talking about barrel extension (the part treaded on to the barrel that actually goes in the upper reciever) The M4 feed ramps are longer and extend into the upper itself. The A2 just had the ramps in the extesion itself. If you have a M4 upper and an A2 style barrel extension it will create a sharp ridge in the feed ramp. This was going to be my suggestion to look for as well. Edited January 2, 2012 by Shooter115 Link to comment Share on other sites More sharing options...
gerritm Posted January 2, 2012 Author Share Posted January 2, 2012 Check that your barrel extension and upper are both compatible You cant have an a4 upper and an a2 extension Jim When you say A2 extension. Do you mean the buffer tube? We did change out the stock including the tube but not the spring and buffer. gerritm He's talking about barrel extension (the part treaded on to the barrel that actually goes in the upper reciever) The M4 feed ramps are longer and extend into the upper itself. The A2 just had the ramps in the extesion itself. If you have a M4 upper and an A2 style barrel extension it will create a sharp ridge in the feed ramp. This was going to be my suggestion to look for as well. How do I tell? Link to comment Share on other sites More sharing options...
GentlemanJim Posted January 2, 2012 Share Posted January 2, 2012 If the gun is short cycling it can also create the problem you describe Remove the upper and bolt carrier Look at the feed ramps from the bottom rear You should be able to determine the configuration Jim Link to comment Share on other sites More sharing options...
stein Posted January 2, 2012 Share Posted January 2, 2012 (edited) Pictures of different feed ramp configurations. Stolen from another forum Edited January 2, 2012 by stein Link to comment Share on other sites More sharing options...
59Bassman Posted January 2, 2012 Share Posted January 2, 2012 Check that your barrel extension and upper are both compatible You cant have an a4 upper and an a2 extension Jim When you say A2 extension. Do you mean the buffer tube? We did change out the stock including the tube but not the spring and buffer. gerritm What was the original stock configuration and what did you change it to? Was it a Carbine stock that you changed to an A1 or A2? Or did you happen to go the other way? Link to comment Share on other sites More sharing options...
gerritm Posted January 2, 2012 Author Share Posted January 2, 2012 Check that your barrel extension and upper are both compatible You cant have an a4 upper and an a2 extension Jim When you say A2 extension. Do you mean the buffer tube? We did change out the stock including the tube but not the spring and buffer. gerritm What was the original stock configuration and what did you change it to? Was it a Carbine stock that you changed to an A1 or A2? Or did you happen to go the other way? It had an inexpensive carbine length adj. stock that was too short even with it as long as it went. Changed it to a Magpul CTR adjustable stock from my DPMS 3G. We changed the buffer tube, but kept the original carbine length spring and buffer. The CTR stock added about an inch to the length. gerritm Link to comment Share on other sites More sharing options...
Tizzle Posted January 2, 2012 Share Posted January 2, 2012 Kinda looks like it's short stroking. How far is the brass ejecting from the rifle? I'm going to guess it's a gas issue. First thing to check should be the gas key on the bolt carrier, lower tier AR's generally don't stake the key properly. After that the gas rings become suspect and then a possible alignment issue with the gas block. Link to comment Share on other sites More sharing options...
gerritm Posted January 2, 2012 Author Share Posted January 2, 2012 We switched the stock back to it's original tube to see if that is part of the problem. Here are some pictures of the feed ramp. I don't know if they are good enough to tell if it is correct. Link to comment Share on other sites More sharing options...
mlmiller1 Posted January 2, 2012 Share Posted January 2, 2012 I'm gonna suggest it is short stroking, like Jim said. Have you cleaned the gas tube? I usually squirt cleaner through the tube until it runs out the barrel clean. Worn out gas rings could also be an issue. If the bolt doesn't come all the way back far enough to eject the spent round, it then goes forward & starts picking up the new one, but the new one can't fit, obviously, so it slams the new round into the feedramps at an angle, bending the round. Is gas blowing out around your gas block, by any chance? A little is not a big deal but a lot is a gas block issue. Do you lube the gun pretty heavily? I used to use slide glide but started having short stroking a occasionally so I went to Rem oil or FP-10(my favorite)& now lube the bolt pretty heavily. I've had fewer failures since then. MLM Link to comment Share on other sites More sharing options...
gerritm Posted January 2, 2012 Author Share Posted January 2, 2012 I'm gonna suggest it is short stroking, like Jim said. Have you cleaned the gas tube? I usually squirt cleaner through the tube until it runs out the barrel clean. Worn out gas rings could also be an issue. If the bolt doesn't come all the way back far enough to eject the spent round, it then goes forward & starts picking up the new one, but the new one can't fit, obviously, so it slams the new round into the feedramps at an angle, bending the round. Is gas blowing out around your gas block, by any chance? A little is not a big deal but a lot is a gas block issue. Do you lube the gun pretty heavily? I used to use slide glide but started having short stroking a occasionally so I went to Rem oil or FP-10(my favorite)& now lube the bolt pretty heavily. I've had fewer failures since then. MLM Cleaned the gas tube. You can see a little gas coming out of the pin in the gas block. Not very much. Nothing anywhere else. I have used slide glide on the wear areas of the bolt, but very sparingly. We reinstalled the original shorter buffer tube. Took it out to the range and fired about 100 rounds thru it with no failures. Used Lake City .556, Federal .223, and PMC .223. Ejected the shells a good 6 feet away. Not sure if that solved it, but we will see in the next match. But that has been the pattern, typical Murphy's Law. Works at the range, but quits during a match. gerritm Link to comment Share on other sites More sharing options...
mlmiller1 Posted January 2, 2012 Share Posted January 2, 2012 I stopped using slide glide for my AR altogether. I use copious amounts of fp-10. It does sound like it may have been the buffer tube. Any chance you may have been flexing the other tube, perhaps with side pressure on the stock? That could(if it is possible) give random failures. Not sure if it's possible, though. MLM Link to comment Share on other sites More sharing options...
gerritm Posted January 16, 2012 Author Share Posted January 16, 2012 It happened again. He shot about 150 rounds thru it after changing back to the original buffer tube and we thought it was solved. Saturday's match when he went to load one in the chamber for the start of the stage and released the bolt it double fed and jammed. He is getting pretty good at clearing it. Got it going and shot about 30 more rounds and it did it again. This time it was while he was shooting. Cleared this one and continued. I have a spare BCG and changed it out and the rifle ran fine for the rest of the match, but this has been the pattern. Run for 100 plus rounds and then these double feed jams. Can happen while loading or shooting. This was a totally different mag than he has used before. The only common part are all of the mags are P-mags. Bad news cause it seems to happen during matches and at the wrong time. Is it possible that he he jamming the mag past the stop? Not sure what could cause it to pick up 2 rounds. Any help is greatly appreciated. gerritm Link to comment Share on other sites More sharing options...
dchang0 Posted January 16, 2012 Share Posted January 16, 2012 (edited) Feed ramps look okay, although they look like the receiver ramps were hand-cut with a file (could be the tiny photos, though). If they ARE hand-cut into the receiver, you should check to see if they were cut correctly (line up properly, have correct angle to match the ramps in the barrel extension, are polished smooth). If I were you, I'd go to the range and hand-cycle rounds quickly through the rifle without firing them. Pull the charging handle all the way back and let the bolt slam forward to pretend you're actually firing the gun. Then check the bullet tips, case mouths, and case shoulders for scrapes and scratches. If the bullet tips are scraped, you definitely have a feedramp problem. One of my friends had a carbine buffer tube whose internal geometry was wrong--it caused short-stroking because the spring and buffer couldn't go all the way back into the tube. But you did try two different buffer tubes already. There is one other possibility I can think of--if your magazines are seating too low in the lower receiver, the angle that the first round in the magazine has towards the barrel extension is too steep, causing hang-ups and failures to feed with the bolt crushing the top of the brass case. You should put that upper on a totally different lower and test it for a bit (that will also help you diagnose the buffer tube at the same time). If it turns out to be that the mags sit too low, you'll likely have to tighten or replace the magazine catch. Much less likely is the possibility that the lower receiver itself has the magazine catch cut too low. Edited January 16, 2012 by dchang0 Link to comment Share on other sites More sharing options...
gerritm Posted January 16, 2012 Author Share Posted January 16, 2012 Stupid question, but what actually picks up the shell on the forward motion of the BCG? Is it the bottom lug? We took it back apart and compared the BCG from my DPMS and his and the lugs on his BCG were quite a bit thicker in width. Is that normal, do the bolt parts vary in dimensions? The top of the mag catch was scored. His BCG is different than my DPMS. Checked where the mag seats and it looked OK. Mag catch is brand new and looks good and solid. Mags lock up. gerritm Link to comment Share on other sites More sharing options...
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