Pro2AInPA Posted October 3, 2010 Share Posted October 3, 2010 (edited) I took my new JP CTR-02 upper out to the range today and had some issues. I had this one particular malfunction about 10 times in 200 rounds. I will do my best to describe the malfunction. What happened was when chambering a round, the bolt apparently wasn't going far enough forward to lock onto the case of the round. I would pull the trigger and get a click instead of a bang. I would pull the charging handle back and see the round in the chamber. I would take the mag out of the gun and let the bolt go forward on the round in the chamber, and the rifle would then fire that round as normal when I pulled the trigger. What this seems like to me is that the bolt carrier isn't flying home with enough force behind it to lock into battery and get the extractor on the rim of the case. That leads me to believe that I need to get more momentum behind the bolt when it's flying forward to chamber a new round. The setup I am using is the low mass carrier in the upper with a carbine stock. I'm using a regular weight carbine buffer. My ideas for how to fix this: 1. Try a H buffer (maybe a heavier buffer would put more force behind the carrier moving forward?) 2. Use a full weight carrier instead of the low mass carrier (maybe the added mass would give the carrier more momentum and lock up reliably?) 3. Switch from a carbine stock to a rifle stock (perhaps the longer rifle spring has more force behind it and will send the carrier home more reliably?) Let me know what you guys think. I need to get this thing running reliably ASAP for some matches coming up. Here's what it looks like: Edited October 4, 2010 by Pro2AInPA Link to comment Share on other sites More sharing options...
jmurch Posted October 3, 2010 Share Posted October 3, 2010 (edited) If it was me I'd try option 2 first. Fast and cheap test to see if it fixes the problem. I doubt option 3 would do anything and I'm 50/50 on option 1. Jeff I took my new JP CTR-02 upper out to the range today and had some issues. I had this one particular malfunction about 10 times in 200 rounds. I will do my best to describe the malfunction. What happened was when chambering a round, the bolt apparently wasn't going far enough forward to lock onto the case of the round. I would pull the trigger and get a click instead of a bang. I would pull the charging handle back and see the round in the chamber. I would take the mag out of the gun and let the bolt go forward on the round in the chamber, and the rifle would then fire that round as normal when I pulled the trigger. What this seems like to me is that the bolt carrier isn't flying home with enough force behind it to lock into battery and get the extractor on the rim of the case. That leads me to believe that I need to get more momentum behind the bolt when it's flying forward to chamber a new round. The setup I am using is the low mass carrier in the upper with a carbine stock. I'm using a regular weight carbine buffer. My ideas for how to fix this: 1. Try a H buffer (maybe a heavier buffer would put more force behind the carrier moving forward?) 2. Use a full weight carrier instead of the low mass carrier (maybe the added mass would give the carrier more momentum and lock up reliably?) 3. Switch from a carbine stock to a rifle stock (perhaps the longer rifle spring has more force behind it and will send the carrier home more reliably?) Let me know what you guys think. I need to get this thing running reliably ASAP for some matches coming up. Edited October 3, 2010 by jmurch Link to comment Share on other sites More sharing options...
P.E. Kelley Posted October 3, 2010 Share Posted October 3, 2010 What mags? How many in the mag? Patrick Link to comment Share on other sites More sharing options...
Religious Shooter Posted October 3, 2010 Share Posted October 3, 2010 If you haven't done it yet, I'd 1) check the ammo with a Mic or change it with a different brand/primer and 2) clean the gun (chamber, check the extractor, etc.) Link to comment Share on other sites More sharing options...
m134b Posted October 3, 2010 Share Posted October 3, 2010 There are a couple things that can cause this, the lightweight carrier may be some of it, but may not be ALL of it.... Check your magazine and make sure the feed lips are in good shape and aren't damaged. That can cause a lot of drag and remove energy from the BCG. What kind of condition are your gas rings in? If they're way too tight it can cause resistance inside the carrier. you should be able to hold the BCG by the bolt and it not "unlock". If it takes some significant pressure to unlock the bolt in the carrier I'd suggest replacement of the rings just as I would if it fell free under the weight of the carrier. When you replace, make SURE the groove is clean! Once replaced, clean and lube the whole assembly according to the manual. AR's don't like to be dry. Also, make sure you're not riding the charging handle home. Pull it all the way back, and let it go. Or, use the bolt release. (that thing could be dragging on your carrier, but highly doubtful) Next check your extractor, it may have some burrs or a lot of crud built up in it causing it to bind and not slip over the cartridge rim. Hope this helps! Ken Link to comment Share on other sites More sharing options...
Pro2AInPA Posted October 3, 2010 Author Share Posted October 3, 2010 What mags? How many in the mag? Patrick PMAGs. I was shooting groups, so I was only putting 5 in the mag. Link to comment Share on other sites More sharing options...
Pro2AInPA Posted October 3, 2010 Author Share Posted October 3, 2010 If you haven't done it yet, I'd 1) check the ammo with a Mic or change it with a different brand/primer and 2) clean the gun (chamber, check the extractor, etc.) This happened with three different types of ammo. Two of them are my handloads which gage ok, and have never caused an issue in my other uppers. This was the maiden voyage for this upper, so it wasn't a dirty chamber. Link to comment Share on other sites More sharing options...
SteveU Posted October 3, 2010 Share Posted October 3, 2010 Is the adjustable gas set too low to fully cycle? Try to open it all the way up. Link to comment Share on other sites More sharing options...
Pro2AInPA Posted October 3, 2010 Author Share Posted October 3, 2010 There are a couple things that can cause this, the lightweight carrier may be some of it, but may not be ALL of it.... Check your magazine and make sure the feed lips are in good shape and aren't damaged. That can cause a lot of drag and remove energy from the BCG. What kind of condition are your gas rings in? If they're way too tight it can cause resistance inside the carrier. you should be able to hold the BCG by the bolt and it not "unlock". If it takes some significant pressure to unlock the bolt in the carrier I'd suggest replacement of the rings just as I would if it fell free under the weight of the carrier. When you replace, make SURE the groove is clean! Once replaced, clean and lube the whole assembly according to the manual. AR's don't like to be dry. Also, make sure you're not riding the charging handle home. Pull it all the way back, and let it go. Or, use the bolt release. (that thing could be dragging on your carrier, but highly doubtful) Next check your extractor, it may have some burrs or a lot of crud built up in it causing it to bind and not slip over the cartridge rim. Hope this helps! Ken This is a brand new upper, so I wouldn't think the rings need replaced. The feed lips on the mag I was using appear to be okay. I was using the bolt release to chamber the first round. That was when this happened the most, but it also happened once during firing. When I took the gun down to clean it after my range trip, there was some dirt in the extractor groove but certainly not a large amount. Link to comment Share on other sites More sharing options...
Pro2AInPA Posted October 3, 2010 Author Share Posted October 3, 2010 Is the adjustable gas set too low to fully cycle? Try to open it all the way up. Doesn't have anything to do with the gas. The rifle CYCLES fine. The issue mainly happened when chambering the first round from the magazine. Link to comment Share on other sites More sharing options...
SteveU Posted October 3, 2010 Share Posted October 3, 2010 read it too fast. Link to comment Share on other sites More sharing options...
P.E. Kelley Posted October 3, 2010 Share Posted October 3, 2010 What mags? How many in the mag? Patrick PMAGs. I was shooting groups, so I was only putting 5 in the mag. Using the mag as a rest? Happen with other mags? Patrick Link to comment Share on other sites More sharing options...
Pro2AInPA Posted October 3, 2010 Author Share Posted October 3, 2010 What mags? How many in the mag? Patrick PMAGs. I was shooting groups, so I was only putting 5 in the mag. Using the mag as a rest? Happen with other mags? Patrick Nope, bipod and rear bag. I only used one mag with this upper, because I only have on 20 round PMAG and was shooting from the bench. Man, if it was just a magazine issue I'd be very happy. Link to comment Share on other sites More sharing options...
1chota Posted October 3, 2010 Share Posted October 3, 2010 (edited) There are a couple things that can cause this, the lightweight carrier may be some of it, but may not be ALL of it.... Check your magazine and make sure the feed lips are in good shape and aren't damaged. That can cause a lot of drag and remove energy from the BCG. What kind of condition are your gas rings in? If they're way too tight it can cause resistance inside the carrier. you should be able to hold the BCG by the bolt and it not "unlock". If it takes some significant pressure to unlock the bolt in the carrier I'd suggest replacement of the rings just as I would if it fell free under the weight of the carrier. When you replace, make SURE the groove is clean! Once replaced, clean and lube the whole assembly according to the manual. AR's don't like to be dry. Also, make sure you're not riding the charging handle home. Pull it all the way back, and let it go. Or, use the bolt release. (that thing could be dragging on your carrier, but highly doubtful) Next check your extractor, it may have some burrs or a lot of crud built up in it causing it to bind and not slip over the cartridge rim. Hope this helps! Ken plus 1. ARs like lube and cleanliness. also SLINGSHSOT the charging handle in a manly manner. case check ammo. Edited October 3, 2010 by 1chota Link to comment Share on other sites More sharing options...
Pro2AInPA Posted October 3, 2010 Author Share Posted October 3, 2010 There are a couple things that can cause this, the lightweight carrier may be some of it, but may not be ALL of it.... Check your magazine and make sure the feed lips are in good shape and aren't damaged. That can cause a lot of drag and remove energy from the BCG. What kind of condition are your gas rings in? If they're way too tight it can cause resistance inside the carrier. you should be able to hold the BCG by the bolt and it not "unlock". If it takes some significant pressure to unlock the bolt in the carrier I'd suggest replacement of the rings just as I would if it fell free under the weight of the carrier. When you replace, make SURE the groove is clean! Once replaced, clean and lube the whole assembly according to the manual. AR's don't like to be dry. Also, make sure you're not riding the charging handle home. Pull it all the way back, and let it go. Or, use the bolt release. (that thing could be dragging on your carrier, but highly doubtful) Next check your extractor, it may have some burrs or a lot of crud built up in it causing it to bind and not slip over the cartridge rim. Hope this helps! Ken plus 1. ARs like lube and cleanliness. also SLINGSHSOT the charging handle in a manly manner. case check ammo. Unfortunately this isn't the issue. It was clean and lubed and I used the bolt release. I'm not new to ARs by any stretch. This is just the first time I have ever had issues anything like this. Link to comment Share on other sites More sharing options...
P.E. Kelley Posted October 3, 2010 Share Posted October 3, 2010 (edited) Still looking like a mag issue to me. Anyone can make a bad mag now and then. Have you used the lower before? The mag is indexed relative to the lower. Patrick Edited October 3, 2010 by P.E. Kelley Link to comment Share on other sites More sharing options...
Pro2AInPA Posted October 3, 2010 Author Share Posted October 3, 2010 Still looking lake a mag issue to me. Anyone can make a bad mag now and then. Have you used the lower before? The mag is indexed relative to the lower. Patrick Yep I've been shooting this lower for years. I just installed a Timney trigger but I don't see how that could be at fault here. I'll try to get out to the range with some other mags and see if the issue persists. Link to comment Share on other sites More sharing options...
P.E. Kelley Posted October 3, 2010 Share Posted October 3, 2010 Still looking lake a mag issue to me. Anyone can make a bad mag now and then. Have you used the lower before? The mag is indexed relative to the lower. Patrick Yep I've been shooting this lower for years. I just installed a Timney trigger but I don't see how that could be at fault here. I'll try to get out to the range with some other mags and see if the issue persists. Well now that you mention it...the hammer part of the fire control group could create carrier drag... If it does rotate low enough in the receiver. Let's hope it is just isolated to one mag. Patrick Link to comment Share on other sites More sharing options...
P.E. Kelley Posted October 3, 2010 Share Posted October 3, 2010 Still looking lake a mag issue to me. Anyone can make a bad mag now and then. Have you used the lower before? The mag is indexed relative to the lower. Patrick Yep I've been shooting this lower for years. I just installed a Timney trigger but I don't see how that could be at fault here. I'll try to get out to the range with some other mags and see if the issue persists. Well now that you mention it...the hammer part of the fire control group could create carrier drag... If it does rotate low enough in the receiver. Let's hope it is just isolated to one mag. Patrick Link to comment Share on other sites More sharing options...
Jaxshooter Posted October 3, 2010 Share Posted October 3, 2010 I had the same problem with a Sabre Defence upper on my carbine lower. Itwas not chambering the round fully, got the same thing you did click with no ignition. All of the rounds checked on a case gauge also. I then loaded some rounds using a small base die in place of the regular one and the problem was solved. Now I load all my .223 ammmo with the small base die. Have you tried factory ammo? That would be the first thing I would do. Link to comment Share on other sites More sharing options...
Pro2AInPA Posted October 4, 2010 Author Share Posted October 4, 2010 I had the same problem with a Sabre Defence upper on my carbine lower. Itwas not chambering the round fully, got the same thing you did click with no ignition. All of the rounds checked on a case gauge also. I then loaded some rounds using a small base die in place of the regular one and the problem was solved. Now I load all my .223 ammmo with the small base die. Have you tried factory ammo? That would be the first thing I would do. Yes, and the same issue occurred with factory ammo. I have actually figured out what part is the culprit. Details to follow. Link to comment Share on other sites More sharing options...
Pro2AInPA Posted October 4, 2010 Author Share Posted October 4, 2010 I just returned from the gun room and I have figured out which part of the puzzle is the problem. I set out to figure that out by loading 10 rounds into the magazine I was using today and cycling them through the gun by hand. I tried the following bolt/carrier combinations: JP low mass carrier w/ JP bolt: Some rounds failing to chamber LaRue carrier w/LaRue bolt: No issues, all rounds cycled normally LaRue carrier w/JP bolt: Some rounds again failed to chamber JP low mass carrier w/LaRue bolt: No issues, all rounds cycled normally So, as we can see here the common denominator with this issue is the JP bolt, not the low mass carrier as expected. My plan is to run the low mass carrier w/the LaRue bolt until I have time to contact JP and get a replacement bolt, since I really do love how the light carrier feels. Any thoughts on these results? What could cause the bolt itself to be the issue? Out of spec somehow? Link to comment Share on other sites More sharing options...
P.E. Kelley Posted October 4, 2010 Share Posted October 4, 2010 (edited) I just returned from the gun room and I have figured out which part of the puzzle is the problem. I set out to figure that out by loading 10 rounds into the magazine I was using today and cycling them through the gun by hand. I tried the following bolt/carrier combinations: JP low mass carrier w/ JP bolt: Some rounds failing to chamber LaRue carrier w/LaRue bolt: No issues, all rounds cycled normally LaRue carrier w/JP bolt: Some rounds again failed to chamber JP low mass carrier w/LaRue bolt: No issues, all rounds cycled normally So, as we can see here the common denominator with this issue is the JP bolt, not the low mass carrier as expected. My plan is to run the low mass carrier w/the LaRue bolt until I have time to contact JP and get a replacement bolt, since I really do love how the light carrier feels. Any thoughts on these results? What could cause the bolt itself to be the issue? Out of spec somehow? John Paul HAS the answer and will make it right. Patrick Edited October 4, 2010 by P.E. Kelley Link to comment Share on other sites More sharing options...
Bryan 45 Posted October 4, 2010 Share Posted October 4, 2010 JP had some bolts a while back that had too small of a bolt face by a couple thousandths. How old is the bolt? (I know it's in new condition, but is it maybe 18 months old?) Link to comment Share on other sites More sharing options...
m134b Posted October 4, 2010 Share Posted October 4, 2010 Perhaps the lugs have burrs and sharp corners from machining, the gas ring groove or the bearing surfaces are oversized. It may just need breaking in. I've seen some crazy stuff with AR's and M-16's.... Hopefully you've solved the issue Ken Link to comment Share on other sites More sharing options...
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