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Unlikely that the Krieger blank is the problem.
I've seen more than a few chambers from CLE not concentric with the bore but that doesn't explain shooting good then not. More than likely the barrel extension was not tight enough. I had the same thing happen with a 308 barrel from Accuracy Speaks. The first 10 were near 1/2" then it got worse as the day went on. I found the loose extension and re-torqued it but then the gas port was off center. I ended up running it with a canted gas block.
Your issue is likely the that NSR is torqued incorrectly and the barrel nut has loosened - Also you might want to check the face of the receiver where the barrel extension shoulder seats to make sure its perfectly flat. I can't remember the spec on that but its like between 40-75 lbs . It is possible that the got a bad batch of blanks but they would shoot like junk from the get go.
My money is on the above.
We also removed the flashhiders, two different types by the way, and still no improvement. My guess is bad blanks and/or chambers were cut out of whack.
Both guns group, then begin stringing vertically and horizontally. Yeah I know...it's a mess.
Krieger blanks were definitely the problem. We will have the new ones Monday. Frank test fired these and assured us they were good to go. We will see.
Loosened and tightened several times. Barrel nut/rail was still aligned. My friend upper was put together with a KAC urx keymod and torqued to 65 in.lb. this was KACs spec. and still no go.![]()
Sorry but I don't believe that for a minute. I've been using(chambering and building with) Krieger blanks for about 20 years and I have never seen a bad one. I sent CLE 70 blanks last year in one shipment and more than half came back to me with the throats not concentric on the bore, chatter and rough chambers. I'll trust Kriegers proven quality over CLEs work any day.
Couldn't agree more... CLE is popping smoke. Waiting for the mirrors to arrive.
uhhhh.... come again?
Krieger looked at the pics and said the barrels looked like they had 3000+ rounds on them. So if Krieger agrees I don't know what is the issue.
Are you saying that the URX 4 Keymod Rail system that acts as the Barrel Nut itself, is only calling for 65" lbs? You sure you didn't mean Ft. Lbs?
90% of the time vertical and horizontal stringing is the shooter behind the rifle. Let someone else shoot it and see what it does. It's in your head now that it's not shooting well.
FTW I got a bad barrel from Krieger about 2 years ago. Would put 3 rounds on top of each other, then start throwing them everywhere. After letting the barrel cool, it would consistently put 3 on top of each other. I did everything I could with the rifle before settling on the barrel. I sent it to Krieger and they said it was a barrel issue and replaced it for me. Excellent service from Krieger and I consider them a top company. However even the best make mistakes.
Actually it looks like you can get them from krieger:
DCM & AR-15
ETA: Nevermind, these are unchambered.
And this is one part of the gun industry that pisses me off. Everything is a secret....................
Wait, don't tell me that you think we should all be able to find out who really makes the various components in our AR 15s. Those rollmarks cost $$$![]()
Well got the barrels today.
Barrel 1- put 30 rounds though it. Best groups was roughly 1.3" but most were 1.6"-2.0". Same garbage. Shoots groups then strings then groups again. The more we shot it the worse it shot. We let it cool shooting no more than 15 rounds between cooling periods. What a WASTE OF TIME! Gas showed erosion when we got them with 47 rounds on them from compass lakes test firing. After 30 more it showed a change in the gas port...more erosion and a shit ton of coppering from the gas port to the muzzle.
Different shooters different ammo. Something is terribly wrong here. Now I'm pist. I'm tired of wasting time and ammo messing with shit that don't shoot. I am quite confused with all of this. I will be contacting compass lake in the morning.
What is really the problem......who knows.
This thread is a source of considerable considerable interest for me. I've been giving it a lot of thought, and I have a theory.
The gas port erosion photos above are 100% typical of the early erosion downstream of the gas port in a new stainless barrel. Yep, that's unfortunately what they all seem to look like. With continued shooting - and cleaning - this erosion becomes more - eroded! - and more smoothly contoured.
I've broken in a lot of AR' barrels. I've made myself literally nauseous peeking inside barrels with a borescope for countless hours. I've noticed a two parallel trends:
1. A new high end, premium barrel will shoot considerably sub-MOA the first group on paper at 100 yards. The gas port is newly cut, with crisp edges. Awesome! Shooter/builder congratulates self, goes home, and has a beer.
2. After the first few groups, accuracy falls off. Multiple cleaning will not restore the accuracy. Frustration builds. Ammo, scope, scope mount, cleaning techniques, suppressor and suppressor mount, trigger, and (mostly) self are all roundly cursed. The gas port erosion has begun, usually with a big chunk of steel crudely evacuating downstream of the port, just exactly like shown in the photos. Frustrated, the shooter goes home and has a beer. Maybe more than one.
3. After more shooting (and more cleaning), maybe 100-200 rounds, the accuracy mysteriously returns. The gas port erosion has progressed to the point that the rough contours have abated. The heavy copper fouling downstream of the gas port lessens. Shooter congratulates self, goes home, has a beer, and doesn't contemplate what really has happened.
I love KG Industries cleaning products. KG-2 is a great cleaning product for a new barrel or an extremely copper fouled barrel. It's a 1200 grit, non-imbedding polish. If I'm going to knock any rough edges off a gas port - or clean up the tool marks in a new throat - it's a lot faster and less expensive to do it with KG-2 on VFG felt pellets than shooting SMK's down the barrel. Or Tubb Final Finish bullets.
KG-2: KG-2 Bore Polish: Metal Protective Coating | Firearm Lubricants | Industrial Coatings
VFG felt pellets: WEAPONS CARE SYSTEM PELLETS | Brownells
BTW, I'd love a brief tutorial on how maggitas was able to take such good photos through a borescope.
Now the hunt is on for another barrel.