I got the Black Enhanced ACR yesterday. I have really spent a lot of time looking at it and I love it. But I have a problem which is not new to the forum.
The problem is barrel alignment and I would like to post a few observations that I have not seen mentioned anywhere else.
I think when many people talk about and post pictures about barrel miss-alignment, they are looking at the relationship to the gas cylinder to the front of the upper, where the gas cylinder is noticeably closer to one side then the other - at least this is what I see in many pictures.
I really looked at the mating surfaces and did a lot of measurements today. My conclusion for my rifle is a little different than many of you.
1) The gas cylinder is about .040” to the left of center it is easy to see because it is runs in a narrow space in the upper.
2) When the bottom hand guard is removed and the barrel alignment is visually checked, it is difficult to see the .020” deviation, very difficult, but it becomes apparent with calipers.
3) The gas piston rod binds in the hole in the trunion that it passes though and with the cocking handle assembly removed from the rifle and the gas piston rod hole in the trunion back lit, one can visually see it binding on one side. That side is the left side of the hole and this matches the left deviation of the gas cylinder. By the way, the gas piston rod appears to be straight as an arrow.
4) Besides a small left deviation of the barrel the gas cylinder has twice that deviation; this could not be true unless the gas cylinder is miss-aligned rotationally or the barrel is not indexed correctly or the there is a problem with the barrel extension.
5) The feed ramps of the extension appear to be spot on rotationally and the indexing slot in the trunion also looks good.
I intend to take it to a friend of mine that is Class 2 manufacturer and get his appraisal to see if it matches mine.
Most of the problems I mentioned will simply go away if the barrel extension position, rotationally , can be adjusted and still maintain the proper torque and head space.
Anyhow, I love the concept of this rifle and I hope the darn thing will work for me. Certainly having proper alignment of the gas system will be a plus to reliability and wear and I will feel better knowing it is right.
By the way, I got this rifle yesterday brand new and have not fired a shot – the temperatures here are pretty close to zero so it is not like I am sitting on my hands.
Its serial number is in the early 3,300 range for those that would track the numbers…I do not know where BM became aware of alignment problems. Maybe I should just send it to them and, from what I have heard, they might gift me several PMags!
It is New Years Eve, happy New Year to all and good shooting!
The problem is barrel alignment and I would like to post a few observations that I have not seen mentioned anywhere else.
I think when many people talk about and post pictures about barrel miss-alignment, they are looking at the relationship to the gas cylinder to the front of the upper, where the gas cylinder is noticeably closer to one side then the other - at least this is what I see in many pictures.
I really looked at the mating surfaces and did a lot of measurements today. My conclusion for my rifle is a little different than many of you.
1) The gas cylinder is about .040” to the left of center it is easy to see because it is runs in a narrow space in the upper.
2) When the bottom hand guard is removed and the barrel alignment is visually checked, it is difficult to see the .020” deviation, very difficult, but it becomes apparent with calipers.
3) The gas piston rod binds in the hole in the trunion that it passes though and with the cocking handle assembly removed from the rifle and the gas piston rod hole in the trunion back lit, one can visually see it binding on one side. That side is the left side of the hole and this matches the left deviation of the gas cylinder. By the way, the gas piston rod appears to be straight as an arrow.
4) Besides a small left deviation of the barrel the gas cylinder has twice that deviation; this could not be true unless the gas cylinder is miss-aligned rotationally or the barrel is not indexed correctly or the there is a problem with the barrel extension.
5) The feed ramps of the extension appear to be spot on rotationally and the indexing slot in the trunion also looks good.
I intend to take it to a friend of mine that is Class 2 manufacturer and get his appraisal to see if it matches mine.
Most of the problems I mentioned will simply go away if the barrel extension position, rotationally , can be adjusted and still maintain the proper torque and head space.
Anyhow, I love the concept of this rifle and I hope the darn thing will work for me. Certainly having proper alignment of the gas system will be a plus to reliability and wear and I will feel better knowing it is right.
By the way, I got this rifle yesterday brand new and have not fired a shot – the temperatures here are pretty close to zero so it is not like I am sitting on my hands.
Its serial number is in the early 3,300 range for those that would track the numbers…I do not know where BM became aware of alignment problems. Maybe I should just send it to them and, from what I have heard, they might gift me several PMags!
It is New Years Eve, happy New Year to all and good shooting!
