ACR Forum banner
1 - 20 of 22 Posts

·
Registered
Joined
·
226 Posts
Discussion Starter · #1 · (Edited)
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!
 

·
Registered
Joined
·
2,790 Posts
There has been some mention of gas piston rod binding, isolated, but mentioned. My piston is straight and has no signs of offset ware. IIRC, the guy that had the problem realigned the rod guide halfway down the barrel and the binding went away. Shouldn't be like that from the factory though.

Please report back what your Class2 friend say about it.

Happy New year and may prices of .223 continue to fall!!
 

·
Registered
Joined
·
226 Posts
Discussion Starter · #4 · (Edited)
cjt50,
The guide will need to be adjusted as you say. Currently the rear end of the piston rod is aligned properly longitudinally in that it is dead center above the indexing pin. The main problem is the timing of the barrel extension, it was turned past the correct point during tightening. So once the barrel is timed properly and the gas piston guide is re-adjusted for the new timing most of the problems will be taken care of. I mean right now, with the hand guard off and the gas piston spring and gas cylinder plug removed, right now there is so much friction at the trunion that you can clearly hear the friction as it slides back and forth at that point!
Re-timing my barrel should also make the gas cylinder center up nicely when viewed from the front with the upper receiver as a reference.
Anyhow, I should have more details in the coming week...
 

·
Registered
Joined
·
226 Posts
Discussion Starter · #5 ·
Question... is the piston rod pictured here suppose to look like this or did a piece break off? I appreciate a helping hand...having a new ACR I have no point of reference. THX
losman, yes, that is how mine looks too. I am not smart enough to know exactly why it is designed that way. Perhaps it is self cleaning or an anti-fouling design.
 

·
Registered
Joined
·
2,790 Posts
losman, yes, that is how mine looks too. I am not smart enough to know exactly why it is designed that way. Perhaps it is self cleaning or an anti-fouling design.
Thats why it's shaped like that, atleast that's what BFI is saying.

losman; your good to go, it's supposed to be like that.
 

·
Registered
Joined
·
226 Posts
Discussion Starter · #8 · (Edited)
About the question above to with the gas piston, I saw this on shooterreviews.com:
"Something we hadn’t really payed attention to during our initial inspection of Bushmaster’s ACR is a very cool feature built into the piston head. The piston actually has a carbon cutter built into it that helps it stay cleaner, for longer, than other piston designs. The design actually causes the piston to rotate and scrape away carbon buildup with every shot. We also learned more about how the gasses are expelled and found yet another improvement of other piston driven designs. Rather than blowing the gasses back towards the inside of the foregrip, the ACR has a single exhaust port pointing straight forward just below the gas valve pushing any excess gasses away from the shooter and the rifle.
Basically, the Bushmaster ACR just keeps getting better and better the more familiar we become with it!"

Excuse me, you guys have probably seen this: I am a little late to the show.

Also there is a short video review there discusing a Bushmaster proto-type hand gaurd - looks to me like one of the Remington handguards I saw...
 

·
Registered
Joined
·
1,587 Posts
Thats why it's shaped like that, atleast that's what BFI is saying.

losman; your good to go, it's supposed to be like that.

Yep. Like on the ol' M60 and its fluted carbon cutters on the op rod.
 

·
Registered
Joined
·
226 Posts
Discussion Starter · #10 ·
Guys, this is a little more complicated and expensive than I thought. I will take this up with BM on Wednesday and report all. I think I will have to send it back because of the cost issue I mentioned to do the repairs my self - $56 dollars to begin then more depending what happens with the index pin - it was probably driven through the barrel extension into a hole the barrel threads themselves to lock everything together as an assembly. So if I were to take this on as a project of my own I could easily plan on a tool cost of $100, a barrel extension and pin for $25 - $35 , a barrel $200 + and costs to refinish. I could probably do a half assed job reusing all the parts I have but I would still have the tool costs and labor.
I think it is a better idea to talk to BM Wednesday.
I work 13+ hours a day, Wednesday is the earliest I can contact them. I will update the results and my thoughts and plan at that time...
I am still excited about this rifle even though I have not shot it yet, there are so many neat things to like!
 

·
Registered
Joined
·
226 Posts
Discussion Starter · #11 ·
It is January 07, I just talked to Bushmaster Customer Service. They will E-mail an insured shipping label to me.
The representative was great to talk to, I detailed my observations, he said they will look at my rifle, determine the problems and replace the barrel and or trunion as needed.
I expected a cat fight to get the gun looked at based on past experience with other customer service representatives (not Bushmaster).
This is my second Bushmaster rifle and my first call to them; so far I am very pleased with the results of the call...
He said if they replaced the barrel, it would be about two weeks so I will wait and report back here when I get the rifle back.
 

·
Registered
Joined
·
279 Posts
good to hear, I'm glad you're taking care of this now, because as you know the factory is closing down and moving to NY/Remington. It's sad to know that 70 of them are going to be out of job come March.
 

·
Registered
Joined
·
226 Posts
Discussion Starter · #13 ·
It is February 10, my rifle returned to me today - I missed the first delivery attempt yesterday.
The barrel and gas regulator seem to be aligned properly both longitudinally and laterally.
The receiver trunion, barrel assembly and gas regulator now are different different than what I sent in.
It looks like I do not have anything to do now but shoot it and when the weather improves I will.
I am very happy with Bushmaster Customer Service they made this as painless as possible - hats off to them!
 

·
Registered
Joined
·
279 Posts
It is February 10, my rifle returned to me today - I missed the first delivery attempt yesterday.
The barrel and gas regulator seem to be aligned properly both longitudinally and laterally.
The receiver trunion, barrel assembly and gas regulator now are different different than what I sent in.
It looks like I do not have anything to do now but shoot it and when the weather improves I will.
I am very happy with Bushmaster Customer Service they made this as painless as possible - hats off to them!
what do you mean different GR? Is the GR have different marking other than U and S? If not, is the gas port a different dimension?
 

·
Registered
Joined
·
226 Posts
Discussion Starter · #15 ·
losman,
Sorry about that! I just meant new as in not the same one I sent in. I still have the U and S markings, the exterior machining marks on the gas regulator are different. I do know that the U and S marks are stamped MUCH deeper now. I do not know the original port dimentions so I do not know if anything is changed there. If you know the original gas port specs, I can measure mine in the next couple of days and post the results back.
I hope you are getting in more shooting than me!
 

·
Registered
Joined
·
2,790 Posts
It is February 10, my rifle returned to me today - I missed the first delivery attempt yesterday.
The barrel and gas regulator seem to be aligned properly both longitudinally and laterally.
The receiver trunion, barrel assembly and gas regulator now are different different than what I sent in.
It looks like I do not have anything to do now but shoot it and when the weather improves I will.
I am very happy with Bushmaster Customer Service they made this as painless as possible - hats off to them!
Always a good report, glad they came thru for you. How long was the wait door to door?
 

·
Registered
Joined
·
226 Posts
Discussion Starter · #17 ·
Always a good report, glad they came thru for you. How long was the wait door to door?
cjt50,
I shipped it on January 11 so it was right at a month in my case. They did tell me if it needed a barrel, it would add about 2 weeks - it needed a barrel!
 

·
Registered
Joined
·
279 Posts
losman,
Sorry about that! I just meant new as in not the same one I sent in. I still have the U and S markings, the exterior machining marks on the gas regulator are different. I do know that the U and S marks are stamped MUCH deeper now. I do not know the original port dimentions so I do not know if anything is changed there. If you know the original gas port specs, I can measure mine in the next couple of days and post the results back.
I hope you are getting in more shooting than me!
Shooting!? are you kidding, I need snow shoes or cross country ski to lay out targets around here in NJ, it's one giant ice sheet out here.
 

·
Registered
Joined
·
350 Posts
Shooting!? are you kidding, I need snow shoes or cross country ski to lay out targets around here in NJ, it's one giant ice sheet out here.
The upside is you can just pound your target stand into the tundra and it holds really well. I even set up out at 100yds. It should be 45 degrees this Sunday into next week. I plan on doing some rifle and pistol shooting.
 

·
Registered
Joined
·
2,790 Posts
cjt50,
I shipped it on January 11 so it was right at a month in my case. They did tell me if it needed a barrel, it would add about 2 weeks - it needed a barrel!
Not bad really considering what was done. More I hear, it sounds like BFI is trying to get it right. Thanks for info.
 
1 - 20 of 22 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top