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Posted: 8/2/2015 4:51:01 PM EDT
| my ar is having some issues it fires 1 shot sometimes 2 then the next bullet gets jammed between the bolt and the chamber... about middle of the bullet is where the bolt lands. and i was able to put a magazine through it that had about 15 rounds and when the last round ejected it never locked back after the last roung |
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CLP clean the rifle, including scrubbing the chamber with a chamber brush and CLP. Use dry patched and get the chamber and bore dry.
Note here, as you have the bolt out of the carrier to clean the B/C, dry fit the carrier with key alone in the upper receiver to make sure that it gliding smoothly. This will confirm that the sides of the key is not too wide, and that the gas tube is correctly indexed with the carrier key. Also take a good look at the chamber condition, hence the chamber walls should smooth as a babies ass, with no reamer chatter (ridge or grooving). As you are putting the B/C back together, flip the B/C upsides down, and look that the firing pin stop collar. The stop collar should be flush to the carrier end of ramp, and not protruding way above the ramp instead. I bring this up, since a M-16 FP stop collar is much larger in OD than a semi FP, and if a M-16 FP is used in a semi, the collar will catch on the hammer as the B/C is moving forward, and lock the B/C up with the bulllet tip just about starting to enter the barrel extension. 
Next, pull the mags apart and clp clean them as well. When you have the mags apart, run your finger down the bottom of the feed lips and if they have burs, then use a stone to remove the burs to leave the bottom of the feed lips smooth. Note, if you are using clone mags, some of them are not formed correctly, and will cause feeding problems in themselves. As for lubing the upper receiver bearing areas, just spray the B/C inside and out with CLP on the heavy side, insert it into the upper, lock the upper home and empty cycle the rifle a few times to migrate the CLP off the B/C to the upper bearing areas. Take a look at the mag release button, and make sure that the threaded end of the catch assembly is flush with the face of the mag release button. If the threaded section end is not flush with the end of the button face, then shove the button all the way in with a pencil, and on the other side of the receiver, turn the mag catch the needed amount of turns. Next, shotgun the upper open, make sure that the bolt catch is not binding in the lower slot (but has spring tension pulling the bolt catch down, insert a empty mag into the well, and make sure that the empty mag follower is pushing the bolt catch all the way up. Lock the upper home, and now use the charging handle to pull the B/C all the way back with a empty mag in the mag well, lock the bolt back on the catch. When pulling back on the charging handle, the face of the bolt should stop around 1/8" to 1/4" in front of the back of the ejection port window edge, and the last 1"ish pull of the charging handle should not be greater in tension them the middle stroke of the charging handle pull (if the tension needed on the handle becomes greater, then chances are you have the wrong recoil spring in play). Now with the above out of the way, insert a single round in the mag, insert the mag and charge the round. With the round fired and the empty mag still in the rifle, did the bolt lock back on the bolt catch (catch holding the bolt back via the face of the bolt). If the bolt did not lock back, then the problem at hand is that the rifle is short stroking. Here the problem could be a leak or blockage of the gas system, either in the gas block and gas tube to barrel, or carrier key to top of carrier, or if you are running a H buffer, the buffer too heavy for the ammo being used. If the bolt does lock back, then we know that the rifle is stroking correctly, and if a feeding/lock up problem instead. Start with the barrel feed lips and if the back inside edge of the feed ramps have a slight burs, then use 400 sandpaper on a chop stick to remove the burs on the back ends of the feed ramps. Next take a good look at the entry taper into the chamber. The chamber back edge should have a taper that allows the case to angle feed smoothly into it. These are smooth feed ramps with the correct chamber entry radius, 
This is a nightmare upper, with both some light feed ramp burs at the end of ramps, but more so, the edge of the taper to chamber wall edge way too sharp and the edge cutting into the side of the brass as loading instead. 
So clean and retest the rifle with a single round, and get back to use if the rifle is full stroking (lock the bolt back) to begin with or not, and we can go deeper into the repairs if needed. Also, If you are breaking the rifle in with surplus, steel coated ammo, or reloads, this may be the problem, so try to run the rifle with some Brass case USA New ammo instead to weed out ammo problems. |
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