AR Sponsor
Posted: 7/29/2014 4:41:18 PM EDT
|
I built my AR on a Vulcan polymer lower,rock river parts kit checked and rechecked, the upper is Double Star factory upper, Mag is a colt mag that has always worked in every rifle it was put in. Cleaned the parts and chamber , volt and carrier, Loaded 1 round fired and locked back from the empty mag. loaded 2 rounds fired one then it would not fully seat on the second round, I re cleaned all parts, have checked the gas port and tube. It will always stop just short of lock up. Forward assist will not move it, I can pull the charging handle back about 1 1/2 inches, just to check to see the brass let it go and it will then fire but then it is the same thing again. I'm at a lost , never had this one before at all. and help or suggestions will be greatly appreciated. I've tired 3 different mags and I am using PMC Bronze 55 grain FMJ-BT factory ammo.This is not the first one I have built, It is the 3rd one.
Thank you in advance Ky- Blacksmith |
|
Pull the bolt off the carrier and using the carrier and key, dry fit it into the upper receiver to make sure that the gas tube is correctly aligned with the key and the carrier is not binding in the upper receiver channel (should glide freely).
Also, would help to know if you are running a O ring around the extractor spring for extra tension, and if you are, remove it. About all I have left to think of (short of some other small glitch areas that we may have to dive into if) is the upper bearing areas (including the buffer and spring) are not lubed well enough and causing the binding problem. |
|
Since it's a new build, I'm inclined to blame it on a rough feed ramp on one side - since the mag feeds from alternate sides. Check the feed ramps for roughness or burrs.
If you can't wait for it to wear in over time, hit the rough spots with a file or stone until the roughness is gone. |
|
thank you both for your suggestion. I checked all the alignment of the the carrier and gas port. Everything seem to fit correctly. I re cleaned and re lubed it well then checked and did find what I thought was a burr or two. Taking it back apart and hitting them with a smooth diamond rod lightly. I put it all back together and tried it again. Still did not feed , however this time one hit on the forward assist and it worked. Before no matter how much I used the FA it would not work. I error-ed on the side of caution but it is working the burr off more each time, BTW I did not have an o ring on it, As for the Vulcan lower it was a gift from someone who was trying. Thought Id give it a try as it lightens the weight by about a pound, Good for a yote rifle you carry around all day.
Thank you for the help Ky-Blacksmith |
| Could be an extractor issue. Had one once that was not machined properly and the part of the hook that mates with the case was flat rather than rounded and it would not allow the bolt to fully seat into battery as it was not catching the case rim but rather getting stuck on it. Was very annoying but some light filing and cold blue fixed it. |
AR Sponsor