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93
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Posted: 9/3/2010 10:28:19 PM
[Last Edit: 9/8/2010 11:47:43 PM by 93]
I just got my ACR and loved it until I took it to the range to zero it. I dd not have a lot of time before dark so I got the irons close and mounted the EOTech. I am shooting from a bench at 100 yards with a bipod on the front and sandbag on the rear of the gun. It is very solid. I could not shoot a good group for love or money but it was getting dark and the car headlights just were not enough to see the target as clearly as I would like to.

I took the rifle back to the range this afternoon and tried again. I got it zeroed but the groups are crap. It is stringing a bit vertically and I can barely keep the shots on an 8.5x11 piece of paper. I tried removing the barrel and putting it back on and cranked the lever as tightly as I could. I am within two detentes of running out and bent the hinge mech. on the lever a bit (not using any tools) to no avail.

I was using an old 20 round mag and the gun failed to lock back several times on the last round and the mag actually fell out a few times. This may be mag related but it works 100% in an AR.

I plan on trying some different ammo, I was using Georgia Arms 55 grain re-manufactured ammo which has always worked well for me, and mounting a 6x Sightron target scope on the rifle to see if some of it may be me but I have gotten better groups off hand with an AR.

I wanted to see if anyone had other suggestions or experience with this sort of problem and try some other ammo before contacting BM.

Typical 10 shot group:

bigdog200399
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Posted: 9/3/2010 10:47:17 PM
where you at in ohio??? i am getting 1 moa groups with mine using an acog, someone here had the problem with his barrel being completely locked in and still was loose, so bushmaster made a custom spacer to fit between the wrench and barrel extension
Gthirteen
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Posted: 9/3/2010 10:47:54 PM
sorry to hear that. I must suggest that you first try no optic at something like 20 yards for groups, then, try a different optic magnified at 50 (if you have access) as it is possible that your optic or mount is causing the issues, also, try a different brand of ammo, then try different weight (but that should be about right for 1/9) and finally try another mag.

your results are not typical.

good luck!!!
93
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Posted: 9/3/2010 11:00:31 PM
Originally Posted By bigdog200399:
where you at in ohio??? i am getting 1 moa groups with mine using an acog, someone here had the problem with his barrel being completely locked in and still was loose, so bushmaster made a custom spacer to fit between the wrench and barrel extension


I think the barrel is tight, I still have 2 clicks to go. I expect that as the gun is shot and the threads seat I will use those two clicks up but I need it to shoot straight before I worry about that. I have a TA11H-G on back order for the gun. I mounted the EOTech for a 3-Gun weekend after next.

I am on the West side of Cincinnati.

omd
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Posted: 9/3/2010 11:08:37 PM
I would not worry too much about it. You're using BUIS and an Eotech, non-magnified and the barrel is new.

Using lower quality ammo I had a few 3-4 " groups at 100 yards using a scope when the ACR was new. It took the barrel and barrel mount about 400-500 rounds to settle in. After that , with good ammo, I routinely get 1.25-1.5" groups using a scope on 9x.

Using a non-magnified Aimpoint T-1, the best I can do is 3-4" and using BUIS, with my eyes, 4"-6" is good for me.
That's a result of the shooter's eyes.

Use the scope, that will help tighten the groups quite a bit. I would hope that you can eventually get 2-2.5" groups using a 6x scope.
Mine seems to like Remington 55gr FMJ's, most good quality 62 gr , 69 gr and 75 gr ammo.
ralexander69
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Posted: 9/3/2010 11:33:32 PM
I was using Georgia Arms 55 grain re-manufactured ammo which has always worked well for me


I hate to say it, but I think this is your problem. Your groups are all over the place because of your ammo choice.
Raizo_Sekai
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Posted: 9/4/2010 12:12:25 AM
Originally Posted By ralexander69:
I was using Georgia Arms 55 grain re-manufactured ammo which has always worked well for me


I hate to say it, but I think this is your problem. Your groups are all over the place because of your ammo choice.


although GA 55 gr is not Match grade, the rifle still should do 3-4 moa at its worst with "factory" ammo

im not a fan of the ACR though
PaBambiKiller
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Posted: 9/4/2010 8:59:18 AM
Originally Posted By ralexander69:
I was using Georgia Arms 55 grain re-manufactured ammo which has always worked well for me


I hate to say it, but I think this is your problem. Your groups are all over the place because of your ammo choice.


+1 go and get some American Eagle Tactical XM193 and several other Federal or Privi., one box of each and see what ammo type is most accurate in your rifle.
ForTehNguyen
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Posted: 9/4/2010 10:21:37 AM
[Last Edit: 9/4/2010 10:22:31 AM by ForTehNguyen]
mine gets similar groups to my ARs. I zeroed at 50 yards. My barrel is tightened down to like a 7-8oclock position

Might want to check barrel crown and if the eotech is mounted tight.
Benjamin-Linus
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Posted: 9/4/2010 12:30:21 PM
[Last Edit: 9/4/2010 12:31:31 PM by Benjamin-Linus]
Originally Posted By Gthirteen:
sorry to hear that. I must suggest that you first try no optic at something like 20 yards


This is good advise to rule out any scope issues.. Also, tighen that barrel down as tight as you can... this is what gets most people. I think you should be getting better groups even with that ammo... but it is worth it to try some factory match ammo before you go through the headache of sending it in to Bushmaster to be looked at. Hornady TAP would be a good choice.
inthe605
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Posted: 9/4/2010 1:38:54 PM
You have something wrong wether it is ammo, or barrel related I would guess combo of both. I can get sub-moa groups outa mine with black hills blue box if that matters.

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Rev68
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Posted: 9/4/2010 10:44:29 PM
Just got back from my first range session, 180 rounds of UAE manufactured 5.56 62gr steal core (I have run 500 + rounds of this through my SCAR with out issue, it was making friends 6920's puke so they sold it to me) and 20 rounds of Winchester 5.56 62gr, the ACR just ran, no issues at all, and on the 25/300 zero target I was using most rounds were grouping under 1/4 to 1/5 and this was with the supplied MAGPUL MBUS. No issues with barrel movement, heat etc.

Love this gun.
Blast
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Posted: 9/5/2010 1:46:27 AM
Originally Posted By 93:
I just got my ACR and loved it until I took it to the range to zero it. I dd not have a lot of time before dark so I got the irons close and mounted the EOTech. I am shooting from a bench at 100 yards with a bipod on the front and sandbag on the rear of the gun. It is very solid. I could not shoot a good group for love or money but it was getting dark and the car headlights just were not enough to see the target as clearly as I would like to.

I took the rifle back to the range this afternoon and tried again. I got it zeroed but the groups are crap. It is stringing a bit vertically and I can barely keep the shots on an 8.5x11 piece of paper. I tried removing the barrel and putting it back on and cranked the lever as tightly as I could. I am within two detentes of running out and bent the hinge mech. on the lever a bit (not using any tools) to no avail.

I was using an old 20 round mag and the gun failed to lock back several times on the last round and the mag actually fell out a few times. This may be mag related but it works 100% in an AR.

I plan on trying some different ammo, I was using Georgia Arms 55 grain re-manufactured ammo which has always worked well for me, and mounting a 6x Sightron target scope on the rifle to see if some of it may be me but I have gotten better groups off hand with an AR.

I wanted to see if anyone had other suggestions or experience with this sort of problem and try some other ammo before contacting BM.

Typical 10 shot group:

http://www.hunt101.com/data/500/medium/acr_target.jpg





Wow ...You're a really bad shot :-)
PaBambiKiller
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Posted: 9/5/2010 7:55:25 AM
Originally Posted By Blast:
Originally Posted By 93:
I just got my ACR and loved it until I took it to the range to zero it. I dd not have a lot of time before dark so I got the irons close and mounted the EOTech. I am shooting from a bench at 100 yards with a bipod on the front and sandbag on the rear of the gun. It is very solid. I could not shoot a good group for love or money but it was getting dark and the car headlights just were not enough to see the target as clearly as I would like to.

I took the rifle back to the range this afternoon and tried again. I got it zeroed but the groups are crap. It is stringing a bit vertically and I can barely keep the shots on an 8.5x11 piece of paper. I tried removing the barrel and putting it back on and cranked the lever as tightly as I could. I am within two detentes of running out and bent the hinge mech. on the lever a bit (not using any tools) to no avail.

I was using an old 20 round mag and the gun failed to lock back several times on the last round and the mag actually fell out a few times. This may be mag related but it works 100% in an AR.

I plan on trying some different ammo, I was using Georgia Arms 55 grain re-manufactured ammo which has always worked well for me, and mounting a 6x Sightron target scope on the rifle to see if some of it may be me but I have gotten better groups off hand with an AR.

I wanted to see if anyone had other suggestions or experience with this sort of problem and try some other ammo before contacting BM.

Typical 10 shot group:

http://www.hunt101.com/data/500/medium/acr_target.jpg





Wow ...You're a really bad shot :-)


93
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Posted: 9/5/2010 12:06:16 PM
Thanks for all the replies, except for Blast The barrel is seated correctly and tight. Tight enough that I bent the folding mech on the wrench. I hope this is ammo related but find it hard to believe even crappy ammo would shoot this bad if everything else is working as it should. Regardless ammo is the first thing I am going to change. I'll shoot a few different types of higher quality ammo and see what happens. If the gun is still shooting poorly I will change the sight to rule that out. Hoping it is the ammo though.

Now to find time to get back to the range and figure this beast out before the 3-Gun shoot on the 18th.
93
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Posted: 9/8/2010 11:46:53 PM
I ended up mounting a Nightforce scope on the ACR and took it back to the range to do some accuracy testing with 3 other kinds of ammo. I didn't bother to do a good zero on the scope just on the paper to compare group size. The results are much better (Except the Georgia Arms) but I am still not excited about them. The best group is a bit over 3 inches at 100 yards and that is with hand loads. Am I being unreasonable expecting better out of a $2400 rifle?

Here is the real kicker, and it has to do with that Georgia Arms ammo again. The gun started running away on me. On several occasions it would fire between 2 and 3 rounds. That is why the GA target only has 9 rounds in it. It was hard to count how many extra rounds were fired when the gun would run away, so I was not sure how many more to shoot at it. It did this 3 times during the 10 9 shot string. The gun also fired two rounds one time when closing the bolt! This did not happen with any of the other brands of ammo but it still concerns me, I can't have the gun firing after hitting the bolt release.

I also had one FTE with the Wolf ammo but used a different mag and had no issues with the bolt not locking back or mag falling out.

I think I am going to contact Bushmaster at this point, I just hate the idea of sending the gun back it is such a PITA.

Top Left: Georgia Arms
Top Right: Wolf Military Clasic
Bottom Left: Hand loads a guy at work gave me
Bottom Right: Hornady 55 grn FMJ/BT



DEVIL-DOC
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Posted: 9/9/2010 2:47:31 AM
Send it back, could be a bad barrel. Have you cleaned it??
omd
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Posted: 9/9/2010 10:38:18 AM
Once again, how many rounds through it ?

It takes 400-500 rounds for these barrels to settle in.

Also have you tried any GOOD ammo ????


Your slamfires and doubles are an ammo/primer problem. The best group I have ever shot with Wolf is 2.5-3". PERIOD.
Wolf is not manufactured for accuracy. I no longer waste my time trying to shoot a good group with Wolf.
Good ammo does cost more money than cheap ammo,but it's a lot more accurate.

Why not try some Remington 55gr or even really splurge and get some PRVI or Federal Match and behold the difference.
QCMGR
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Posted: 9/9/2010 11:23:14 AM
Originally Posted By omd:
Once again, how many rounds through it ?

It takes 400-500 rounds for these barrels to settle in.



DEVIL-DOC
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Posted: 9/9/2010 12:59:06 PM
Originally Posted By QCMGR:
Originally Posted By omd:
Once again, how many rounds through it ?

It takes 400-500 rounds for these barrels to settle in.





+1
omd
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Posted: 9/9/2010 6:11:02 PM
Originally Posted By DEVIL-DOC:
Originally Posted By QCMGR:
Originally Posted By omd:
Once again, how many rounds through it ?

It takes 400-500 rounds for these barrels to settle in.





+1


I started getting my best accuracy through mine at that point. Using a 9x scope and good ammo, after about 400+ rounds , I went from 1.5" -2" groups to about 1" at 100yds (supported prone).
Pinoy556
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Posted: 9/9/2010 8:33:58 PM
What about upgrading the trigger? So far, I shot close to 300 rounds and had an acceptable grouping during this break in period. My plan is to upgrade the trigger to 2 stage trigger and hopefully I will get a wow grouping
squirrell18
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Posted: 9/27/2010 11:41:32 AM
[Last Edit: 9/27/2010 11:45:44 AM by squirrell18]
You sure that wasn't a group with my SIG 556? LOL. that sucks, My SIG was getting 12" groups with match grade ammo and the assholes on SIG forums said I wasn't used to the trigger, lol. Turned out my barrel was bad and bolt carrier was slamming receiver.