Zoomy Posted January 15, 2015 Share Posted January 15, 2015 (edited) I have an occasional jamming issue that I think is related to the M4 feed ramps. I have a Mega upper and a Compass Lake barrel that I assembled. As the photos show there is a step that has developed nicks on the barrel extension and upper interface. I have approximently 1300 rounds thru it and it has jammed like this 4 times using Lancer or Pmags. There is also scoring which appear to be caused by the sharp edges on the locking lugs where the feed ramps intersect. I believe this scoring might be causing drag that can effect the feeding and deflect the bullet into jamming on the upper part of the breech. Should I blend the feed ramp area where it transitions the ramp in the upper to remove the nicks and step?Also should I take a diamond jewelry file and smooth out the sharp edges on the feed ramp/locking lug intersection? Any help in understanding and fixing the problem is greatly appreciated. Edited January 15, 2015 by Zoomy Link to comment Share on other sites More sharing options...
WhiteDingo Posted January 15, 2015 Share Posted January 15, 2015 You will want to get rid of that lip. I would blend the barrel ramp to match the upper, either by file/polishing or dremel (carefully). The scoring is likely be due to the sharp edges, If you just break the corner and polish it should reduce the scoring. Link to comment Share on other sites More sharing options...
StealthyBlagga Posted January 15, 2015 Share Posted January 15, 2015 (edited) STOP!!! I would NOT recommend Dremelling on the extension to fix this kind of problem. Are you sure the barrel extension is an M4-type? Looks like it could be a rifle extension, which will not work with an M4 upper. Do you have a rifle (non-M4) upper you can try? If not, check your PM. If the barrel was advertized by Compass Llake as one with M4-ramps, I would call them first, send the photo, and get their feedback... the barrel may have been built with the wrong/a defective extension. Edited January 15, 2015 by StealthyBlagga Link to comment Share on other sites More sharing options...
dauntedfuture Posted January 15, 2015 Share Posted January 15, 2015 (edited) That looks like an A2 extension and an M4 upper to me which COULD be the problem. In general you can run a M4 extension with upper. I have reshaped rifle extensions to M4 extensions with a hand round file. You need to send a pic of what the rifle looks like when there is a jam. I suspect that the system is on the edge of operation. If you have an adjustable gas block open it up a little or use hotter ammo. I highly doubt that that's what is causing your problems. Its more likely another issue related to out of spec parts (not the barrel) magazines, ammunition, operating system, gas, the lower, the bolt catch..... There are lots of possibilities. I think You can get a flat top rifle upper but I don't think that will fix the issue. Whose upper is that? The marks look more like they were caused when the bolt slammed into the top of a half-out of the magazine round but I cant tell for sure. Edited January 15, 2015 by dauntedfuture Link to comment Share on other sites More sharing options...
Zoomy Posted January 15, 2015 Author Share Posted January 15, 2015 (edited) That looks like an A2 extension and an M4 upper to me which COULD be the problem. In general you can run a M4 extension with upper. I have reshaped rifle extensions to M4 extensions with a hand round file. You need to send a pic of what the rifle looks like when there is a jam. I suspect that the system is on the edge of operation. If you have an adjustable gas block open it up a little or use hotter ammo. I highly doubt that that's what is causing your problems. Its more likely another issue related to out of spec parts (not the barrel) magazines, ammunition, operating system, gas, the lower, the bolt catch..... There are lots of possibilities. I think You can get a flat top rifle upper but I don't think that will fix the issue. Whose upper is that?u The marks look more like they were caused when the bolt slammed into the top of a half-out of the magazine round but I cant tell for sure. I built the upper using a Mega upper with a Compass Lake 18" barrel. The barrel is supposed to have the M4 feed ramps. I will check with compass lake. And it appears that the bolt is slamming into the top of the bullet. The photo shows the dents and the bolt lugs line up perfectly. Good call.Could the feed ramp issues cause the bullet to slow Dow or stop the movement into the chamber to cause the back of the bullet to slip back down in the magazine and allow the bolt to ride over the top and dent the case? Edited January 15, 2015 by Zoomy Link to comment Share on other sites More sharing options...
dauntedfuture Posted January 15, 2015 Share Posted January 15, 2015 Again, I highly doubt that its the feed ramp mismatch but it is possible. Tell us more about the rest of the system, what bolt, trigger, gas, block ammo etc. Are you lubing the gun enough? 4 rds out of 1300 is not a lot of malfunctions, im not saying that its great, but in general the rifle runs. If you were having malfunctions every other round or 2 out of a magazine that would be a more serious issue. I am also not saying that you cant work it out but its going to be a little harder. I don't know what kind of chamber is on that rifle barrel but compass lake makes mostly NRA highpower stuff and they usually use their own chamber reamer. I have a suspicion that the chamber is a little more on the tight side then loose and it you have a tight chamber and dirty gun with a little less lube.....bingo malfunction. Remember that you did build this thing out of a box of parts and there is tolerance stacking involved, I have done the same thing many times, im not knocking you, im just saying that its possible that the combination of parts, A+B+C+D = extra tight/ slop etc. As I rethink this, you might just need to clean and lube your rifle. Link to comment Share on other sites More sharing options...
Zoomy Posted January 15, 2015 Author Share Posted January 15, 2015 (edited) Again, I highly doubt that its the feed ramp mismatch but it is possible. Tell us more about the rest of the system, what bolt, trigger, gas, block ammo etc. Are you lubing the gun enough? 4 rds out of 1300 is not a lot of malfunctions, im not saying that its great, but in general the rifle runs. If you were having malfunctions every other round or 2 out of a magazine that would be a more serious issue. I am also not saying that you cant work it out but its going to be a little harder. I don't know what kind of chamber is on that rifle barrel but compass lake makes mostly NRA highpower stuff and they usually use their own chamber reamer. I have a suspicion that the chamber is a little more on the tight side then loose and it you have a tight chamber and dirty gun with a little less lube.....bingo malfunction. Remember that you did build this thing out of a box of parts and there is tolerance stacking involved, I have done the same thing many times, im not knocking you, im just saying that its possible that the combination of parts, A+B+C+D = extra tight/ slop etc. As I rethink this, you might just need to clean and lube your rifle. Here are the rest of my rifle details:- Young National Match bolt and carrier - Voltor A5 buffer and spring - Low profile gas block with mid length gas system. - Mega lower - JP Enterprises EZ Trigger with speed hammer - Compass Lake Engineering 18" SPR barrel 1:8 twist. The Wylde chamber was reamed by Compass Lake and I sent them my bolt and carrier to headspace. - PMC Xtac .223 ammo 55 grain - BCM Gunfighter charging handle Edited January 15, 2015 by Zoomy Link to comment Share on other sites More sharing options...
dauntedfuture Posted January 15, 2015 Share Posted January 15, 2015 I run a 18" midlength DD barrel with A5 buffer system and a RCA LW BCG without issues. I think that PMC ammo is a little on the anemic side from what I understand from some of the other posts. If you have the CLE 18" SPR barrel, it says that on the web site that the 18" barrel has rifle gas. I am not sure if this is a small clerical error or what as I don't think that you can get a rifle length gas to work with a midlength gas tube. From Youngs web site" "This is our signature carrier assembly. Added surface area in the front of the carrier gives a tighter fit when the bolt is in battery for more consistent lock up." It looks like this is a more beefy carrier then a standard one, or it looks like it weighs a little more then a standard one. This added carrier weight combined with some anemic ammunition and a dirty rifle could cause or contribute to your issues. FROM AR-15.com "This is not the 5.56 from the 90s. This is .223 power ammo. Having said that it is good ammo. Not one issue in over 1k rounds thru several carbines. Accuracy could be better, but it is a 55gr. fmj. It averages less than 2800fps out of my carbines. So it definitely is not 5.56 pressure." Link to comment Share on other sites More sharing options...
Zoomy Posted January 15, 2015 Author Share Posted January 15, 2015 I have some Federal M193 5.56 that I a can try. Link to comment Share on other sites More sharing options...
Stlhead Posted January 15, 2015 Share Posted January 15, 2015 Those are rifle ramps in an M4 cut upper. That barrel needs to be in a different upper. I would also not recommend grinding on it, but it is your barrel do whatever trips your trigger. I have enjoyed this particular situation before personaly. Hotter ammo and gas adjustments will not fix the intermittent failure to feed. Get a different barrel or a different upper or both. Link to comment Share on other sites More sharing options...
cking Posted February 7, 2015 Share Posted February 7, 2015 Grind on the barrel feed ramps, get an M4 ramped barrel to copy, or buy a upper without the M$ ramps Link to comment Share on other sites More sharing options...
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