FullEffect1911
Member
Alright, I have posted a lot of my ar15's problems in various sections of this forum. However at those times I thought it was an ammo problem.
The rifle is a 20" bushmaster ar15 A2 with less then 1000 rounds through it. The rifle is very clean.
Here is the situation.
Using various types of factory and handloaded ammunition, the rifle will short stroke and fail to lock after the last round.
Occasionally the bolt will just skip over the next round in the magazine and force me to chamber the next round manually.
Sometimes the bolt will start to pick up the next round, however since the bolt didn't travel all the way back it will jam the round and dent the case. This of course forces me to clear the jam. I believe this would be a 3 point jam.
I do have some powder leaking past the front sight base, however I have come to believe some leakage is normal.
The overwhelming majority of the cases show some shinny scrape signs in the extractor groove. These marks lead me to believe that the rifle is unlocking and trying to extract the case that is still under pressure and pressed up against the chamber walls. This would bleed off momentum of the bolt/bolt carrier and cause short stroking. As I have read this would be an over pressurization of the gas system.
The tube is not bent. The bolt key is tight and still staked. The tube's mushroom looks fine. Malfunctions happen with both my bushmaster and colt mag. Gun is clean, gas system was cleaned with a pipe cleaner, bolt carrier was lubed up nicely and the buffer spring tube has a light coating of oil. The bolt it pretty well worn together with the upper so it is pretty smooth. The bolt will lock on an empty magazine if I do it manually. I am 99% certain it is not ammo related (my most recent ammo try was black hills 55grain).
I have not taken pieces off the gun yet, as I have never fully disassembled an AR, however I would really love to solve this problem and I need help. If anyone has any ideas on where to go from here I would be very appreciative.
The rifle is a 20" bushmaster ar15 A2 with less then 1000 rounds through it. The rifle is very clean.
Here is the situation.
Using various types of factory and handloaded ammunition, the rifle will short stroke and fail to lock after the last round.
Occasionally the bolt will just skip over the next round in the magazine and force me to chamber the next round manually.
Sometimes the bolt will start to pick up the next round, however since the bolt didn't travel all the way back it will jam the round and dent the case. This of course forces me to clear the jam. I believe this would be a 3 point jam.
I do have some powder leaking past the front sight base, however I have come to believe some leakage is normal.
The overwhelming majority of the cases show some shinny scrape signs in the extractor groove. These marks lead me to believe that the rifle is unlocking and trying to extract the case that is still under pressure and pressed up against the chamber walls. This would bleed off momentum of the bolt/bolt carrier and cause short stroking. As I have read this would be an over pressurization of the gas system.
The tube is not bent. The bolt key is tight and still staked. The tube's mushroom looks fine. Malfunctions happen with both my bushmaster and colt mag. Gun is clean, gas system was cleaned with a pipe cleaner, bolt carrier was lubed up nicely and the buffer spring tube has a light coating of oil. The bolt it pretty well worn together with the upper so it is pretty smooth. The bolt will lock on an empty magazine if I do it manually. I am 99% certain it is not ammo related (my most recent ammo try was black hills 55grain).
I have not taken pieces off the gun yet, as I have never fully disassembled an AR, however I would really love to solve this problem and I need help. If anyone has any ideas on where to go from here I would be very appreciative.