Rifle specs first:
.308 Win
Armalite AR10A4
20 inch SS barrel
Replaced original handguards with Troy 2 piece free-float
Replaced original stock with Magpul PRS
Replaced original buffer with "Slash" heavy buffer. (I went to the heavy buffer when I tried shooting FGMM 168 grain and it nearly ripped the rim off the case.)
Stock gas block, non-adjustable or switching.
All modifications to the gun were made last summer. Gun ran fine for a year.
I think that covers everything. If I missed something relevant, just ask.
The symptom while shooting is failure to eject. It appears the the rifle is short stroking. The empty case is extracted from the chamber but not ejected from the rifle. Ejected cases land at about the 3 o'clock position from the gun.
At first I thought it was just dirty or not enough lube. Cleaning and adding lube did not help. But, what I noticed is that the bolt does not move smooth in the carrier. As the bolt is moving out of the carrier (same motion as if extracting a round from the chamber) the bolt "hangs up" just before the gas rings get to the exhaust ports on the carrier. Even if I remove the cam pin so that I only have the resistance of the gas rings in the carrier, the bolt gets hung up at the same point.
I thought maybe the gas rings were the problem. I ordered a new set from Armalite. Installed them and thought I had the problem solved. On the bench, the bolt moved freely in the carrier. However, 15 rounds in the first range trip and I had a fail to eject. Emptied the gun and worked the bolt, and could tell it was getting hung at that same spot again. Took it apart, and sure enough, the bolt was hanging at that same point.
I can't see any signs of damage in the bolt carrier where the gas rings are touching. The gas rings move free in the ring on the tail of the bolt.
I talked to Armalite today, and the conversation came to a bit of a halt when I mentioned a heavy buffer. Their suggest is to try it with the original and see what happens. I asked about the bolt not moving free in the carrier, but he didn't really want to talk about that.
I can try the original buffer easy enough. But I can't help but think that if there IS a problem with the bolt or carrier, the light buffer is only going to mask it over until the failure gets worse. On one hand, at least when it totally fails I'll know what the problem was. But we all know that will happen during the middle of a match or class.
Thanks in advance for any ideas or suggestions.
.308 Win
Armalite AR10A4
20 inch SS barrel
Replaced original handguards with Troy 2 piece free-float
Replaced original stock with Magpul PRS
Replaced original buffer with "Slash" heavy buffer. (I went to the heavy buffer when I tried shooting FGMM 168 grain and it nearly ripped the rim off the case.)
Stock gas block, non-adjustable or switching.
All modifications to the gun were made last summer. Gun ran fine for a year.
I think that covers everything. If I missed something relevant, just ask.
The symptom while shooting is failure to eject. It appears the the rifle is short stroking. The empty case is extracted from the chamber but not ejected from the rifle. Ejected cases land at about the 3 o'clock position from the gun.
At first I thought it was just dirty or not enough lube. Cleaning and adding lube did not help. But, what I noticed is that the bolt does not move smooth in the carrier. As the bolt is moving out of the carrier (same motion as if extracting a round from the chamber) the bolt "hangs up" just before the gas rings get to the exhaust ports on the carrier. Even if I remove the cam pin so that I only have the resistance of the gas rings in the carrier, the bolt gets hung up at the same point.
I thought maybe the gas rings were the problem. I ordered a new set from Armalite. Installed them and thought I had the problem solved. On the bench, the bolt moved freely in the carrier. However, 15 rounds in the first range trip and I had a fail to eject. Emptied the gun and worked the bolt, and could tell it was getting hung at that same spot again. Took it apart, and sure enough, the bolt was hanging at that same point.
I can't see any signs of damage in the bolt carrier where the gas rings are touching. The gas rings move free in the ring on the tail of the bolt.
I talked to Armalite today, and the conversation came to a bit of a halt when I mentioned a heavy buffer. Their suggest is to try it with the original and see what happens. I asked about the bolt not moving free in the carrier, but he didn't really want to talk about that.
I can try the original buffer easy enough. But I can't help but think that if there IS a problem with the bolt or carrier, the light buffer is only going to mask it over until the failure gets worse. On one hand, at least when it totally fails I'll know what the problem was. But we all know that will happen during the middle of a match or class.
Thanks in advance for any ideas or suggestions.