Resolution of Problem in Post 31
The Problem: This new build (details to follow) will consistently jam after the first shot. Empty case from first round ejects clear, second round picked up from mag and goes into chamber almost all the way, but bcg has not locked up or go into battery. Almost there but not quite. Sorry no pictures, but a quick look and you would think it was fine. Forward Assist will not move it forward the last bit. It takes a lot of force to remove the stuck round and get the bcg to the rear. Amount of force required just short of needing to mortar it. Cannot open rifle by removing rear take down pin, assuming BCG not clear of lower It will always go into battery loading the first round from mag, either by working the handle if action closed or releasing bolt if action open. If loading one round in the mag, the rifle will go into battery, and after firing the bcg will lock back on empty mag. If two or more rounds loading into mag, it will always go into battery on first round, and after firing jam on the second round. Relatively new Pmag that functioned fine in another weapon. With dummy rounds or live rounds I can manually cycle through five rounds without issue. Ammo was PMC 5.56 bronze in a lot number of I used in another rifle without problems. I was running upper and bcg wet (break free clp )
The build: The upper is a DTI complete upper, bought from another green member, with a few hundred rounds through it. 16" m4 with target crown. Looks fine. Upper was beautifully cleaned when I received it, but cleaned it myself anyway. It is an AERO lower with Stag Arms lpk that I put together, not my first build but still a relative newbie at EBR builds. BCG is new Aim Surplus NIB . Headspace checked fine with go and no go gauges.
When I function tested it at range, I was there working on Appleseed practice with a .22 ar, and I only had one mag, one type of ammo, and one rifle in 5.56 with me so could not test variables then.
I inspected the lower and did not find any bone headed things I did incorrect on assembly. Upper looked fine, including FA not protruding until pressed. The only thing I am suspect about is the bcg. I had field stripped it, inspected it and lubed it before use. Only thing I noticed is in removing bolt from carrier not only did it not drop out, it took way more force to remove bolt than I had experienced before, almost as if I was creating a vacuum when pulling it out. I did not use solvent to clean bcg prior to lubing it up. Maybe a mistake? will strip and clean and relube before going back to range.
Range Plans: going back Tuesday with multiple new mags, assorted ammo, and another known good AR. Plans are to test and if second round jam still occurs after bcg cleaning do the following
Try different ammo and mag.
Try removing mag after first round loading, and seeing if after discharge does bolt return to battery with no cartridge.
Try another bolt in this rifle (have STAG bcg that has functioned fine for less than 100 rounds in second rifle)
Try the AIM bolt in second rifle
Try this upper on a another lower (with AIM bolt and Stag bolt)
So unless problem has gone away with cleaning bolt, at this point I should know if problem is upper or lower or bcg. (or a bizarre case of stacking tolerances and it only occurs with the initial combination)
I also thought of running through 20 rounds in single shot mode to try to break it in?
Any other thought on what I should look for before going to range or do at the range?
The Problem: This new build (details to follow) will consistently jam after the first shot. Empty case from first round ejects clear, second round picked up from mag and goes into chamber almost all the way, but bcg has not locked up or go into battery. Almost there but not quite. Sorry no pictures, but a quick look and you would think it was fine. Forward Assist will not move it forward the last bit. It takes a lot of force to remove the stuck round and get the bcg to the rear. Amount of force required just short of needing to mortar it. Cannot open rifle by removing rear take down pin, assuming BCG not clear of lower It will always go into battery loading the first round from mag, either by working the handle if action closed or releasing bolt if action open. If loading one round in the mag, the rifle will go into battery, and after firing the bcg will lock back on empty mag. If two or more rounds loading into mag, it will always go into battery on first round, and after firing jam on the second round. Relatively new Pmag that functioned fine in another weapon. With dummy rounds or live rounds I can manually cycle through five rounds without issue. Ammo was PMC 5.56 bronze in a lot number of I used in another rifle without problems. I was running upper and bcg wet (break free clp )
The build: The upper is a DTI complete upper, bought from another green member, with a few hundred rounds through it. 16" m4 with target crown. Looks fine. Upper was beautifully cleaned when I received it, but cleaned it myself anyway. It is an AERO lower with Stag Arms lpk that I put together, not my first build but still a relative newbie at EBR builds. BCG is new Aim Surplus NIB . Headspace checked fine with go and no go gauges.
When I function tested it at range, I was there working on Appleseed practice with a .22 ar, and I only had one mag, one type of ammo, and one rifle in 5.56 with me so could not test variables then.
I inspected the lower and did not find any bone headed things I did incorrect on assembly. Upper looked fine, including FA not protruding until pressed. The only thing I am suspect about is the bcg. I had field stripped it, inspected it and lubed it before use. Only thing I noticed is in removing bolt from carrier not only did it not drop out, it took way more force to remove bolt than I had experienced before, almost as if I was creating a vacuum when pulling it out. I did not use solvent to clean bcg prior to lubing it up. Maybe a mistake? will strip and clean and relube before going back to range.
Range Plans: going back Tuesday with multiple new mags, assorted ammo, and another known good AR. Plans are to test and if second round jam still occurs after bcg cleaning do the following
Try different ammo and mag.
Try removing mag after first round loading, and seeing if after discharge does bolt return to battery with no cartridge.
Try another bolt in this rifle (have STAG bcg that has functioned fine for less than 100 rounds in second rifle)
Try the AIM bolt in second rifle
Try this upper on a another lower (with AIM bolt and Stag bolt)
So unless problem has gone away with cleaning bolt, at this point I should know if problem is upper or lower or bcg. (or a bizarre case of stacking tolerances and it only occurs with the initial combination)
I also thought of running through 20 rounds in single shot mode to try to break it in?
Any other thought on what I should look for before going to range or do at the range?
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