View Full Version : AR accuracy issues
I have a Rock River lower and a DPMS carbine upper. Accuracy is horrible out of it and I am looking to improve. What is a good start to improving accuracy on a budget. Does a free float hand guard make a big difference? The barrel is a 1-9 twist and I have tried both factory 55gr and 62 gr (Fiochi). I have tried reloads with Hornady FMJ and the V-max 55gr. I am using 24.3gr IMR 4895 and commercial ammunition. It has a 5.56 chamber. I have also tried 23.1gr TAC powder with similar results. The rifle has maybe 300 rounds through it. Any suggestions? Do I need a heavier bullet with this twist rate?
the 1/9 twist is designed to stabilize heavier 62-77 gr bullets better than the mil spec 1/7. You should have decent accuracy. I don't care for DPMS so I would suggest replacing the upper....if that's not an option, try several factory loads for comparison, then see what the load data is for the one(s) that work best, and start tweaking from there. If you get nowhere, take to a gunsmith to inspect the upper. Keep in mind, most base carbines are 3 moa guns. If you're looking for cloverleafs, you usually have to pay for it with a good barrel.
I would be happy with 3 moa. Mine is more like 6. A new upper is not in the cards. What is the average muzzle velocity for most factory loads? I am loading to 3000fps according to Hornady's book. How about those free floating hand guards? Do they work? And what barrel would you suggest? I want to keep the same profile barrel.
BPTactical
12-06-2010, 21:03
Accuracy is a subjective thing. Please describe a bit better. Are you grouping ok or are you getting erratic flyers?
Is it hitting what you are aiming at or are you having to "Kentucky Windage" it?
It will help us figure out if it is a mechanical problem or an ammo issue.
COCCW- I have been led to believe that the 1/9 is more of a "all around" twist rate and that it will produce better results with lighter grain weights. The quicker 1/7 favors a heavier grain weight.
Personally I havent noticed much of a difference but I am not an accuracy nut with my AR's either.
If I am incorrect can you refer me to some info?
If you are at six minutes then floating will not help much. It does help if you tend to sling up hard but you should be able to see 2-3 minutes off a bench without a problem.
To see 6 inches I would start looking at my sights. If you have raised your front post to far it can wiggle. Is the sight base tight? If you have a detachable handle it might be loose as well. If scoped, how is the mount? Cheap scopes/reddots can move with recoil.
Are your holding the same? I have seen issues with red dot users with larg moa dots having a hard time with consistancy.
A 1/9 should shoot 50gr - 69gr without a problem. The Fed bulk 55 shoots 1.5 for me at 3300 ft/sec, the American Tac is about the same. Same rifle with 69gr SMK at 2700 ft/sec does .75 inch or so. The bulk stuff will have a flyer every now and then but should group well overall.
COCCW- I have been led to believe that the 1/9 is more of a "all around" twist rate and that it will produce better results with lighter grain weights. The quicker 1/7 favors a heavier grain weight.
Personally I havent noticed much of a difference but I am not an accuracy nut with my AR's either.
If I am incorrect can you refer me to some info?
You are correct, I had it backwards. (Long day & 2 sick kids.....) Good thing I just have the mfg build what I need...
BPTactical
12-06-2010, 21:25
You are correct, I had it backwards. (Long day & 2 sick kids.....) Good thing I just have the mfg build what I need...
Whew!-Thought I steered folks wrong. Thank You[Beer]
Hope the kids feel better before Satan Claws comes[Muaha]
Colorado Osprey
12-07-2010, 06:28
Before replacing the barrel, does it have a comp or flash supressor?
Can you remove it? It could be a slightly bent comp or supressor deflecting the exit gases resulting in instability of the bullet exiting the bore similar to a nicked up barrel crown.
If it doesn't can you closely check the barrel crown? Any nick could be the culprit.
These are some simple causes of poor accuracy that can be easily and cheaply fixed.
OgenRwot
12-07-2010, 11:19
I would be happy with 3 moa. Mine is more like 6. A new upper is not in the cards. What is the average muzzle velocity for most factory loads? I am loading to 3000fps according to Hornady's book. How about those free floating hand guards? Do they work? And what barrel would you suggest? I want to keep the same profile barrel.
Not to knock your reloading practices or anything but did you work up a load or did you just start at 3000 FPS? Every single rifle is different and therefore likes different loads. Start at or below 10% of max and work your way up. Shoot groups of each and see what gets you the best accuracy.
There are a lot of things that can cause it to shoot inaccurate. Too many for me to speculate.
If you do end up wanting a new barrel, I would suggest a Black Hole Weaponry polygonal barrel. They are available in any profile, any length and match grade is also available. These shoot sub MOA and we have been doing a lot of builds with them with no complaints. And as aways, forum members get a discount.
The groups are pretty erratic. I have shot it off a bench with a grip-pod and a rear sight that I guess is a backup sight for the military. I have also used a Burris AR-332 3x prism sight with results that are not much better. I worked up my loads from 22.7gr IMR4895 with no real change in accuracy. I may need to try a better rear sight since the one I have seems a bit cheap and as the name implies a "backup" sight. It does have a flash suppressor that came with the upper. I have looked at it to see any bullet strikes, and there is no apparent problem there. It is the standard M4 type. I think it is removable, I just don't know much about the AR platform or how to tell if it is removable. My front sight isn't adjusted too far out. It is flush with the sight base. I torqued my rear sight to the flat-top to 20in lbs. I do hit what I aim at though. I was always told that AR's are inherently more accurate than say an M1A or Garand. And since Ar's are taking over service rifle, maybe that is true. I'm just not seeing it. Thanks for all the replies.
I don't know where Winsor is but if you want to bring it by, I will take a look at it for you. I can probably tell you whats wrong with it. No charge.
I hope you don't take this wrong but since I don't know your experience I need to ask...
When you are using the iron sights where is your eye focused (rear sight, front sight or target)?
When you are using the scope where is your eye focused (reticle or target)?
Any bucking or flinching when you fire, how is you breathing?
RARGUNS, Windsor is located just south of Fort Collins. Thanks, I may take you up on that offer. Although I have no idea where you are located.
esaabye, I am very experienced with scopes (I work for Burris in repair), and I'm very good with iron sights. 400 yards with an M1A or Garand no problem. And I compete regularly in service rifle and defensive pistol. I placed 1st at the Frozen Chosin last weekend. I focus on the front sight or with a scope, the reticle. My breathing needs a little work, but I am getting the hang of it. Bucking and flinching are a non issue. My trigger on the AR is the crappy single stage DPMS (lots of creep). I'm really not a fan of it since I'm used to the military two stage, and a 4 1/2 lb pull.
I did not mean any offense. At this point you have eliminated the shooter, the sights and the ammo so you are left with the barrel. I don;t see anything else.
We are in Castle Rock. It's about an hour and 15 minutes.
No offense taken esaaybe.
And castle Rock is a little far for me but it still is an option.
If you can't get it figured out, we'll help you out.
Well I took the rifle out to the range today with a known good 3x9 scope and tried my best to print a good group from a bi-pod. I tried several factory loads including PMC 55gr fmj, Hornady 55gr V-max, Fiocchi 62 gr fmj, Lake City 55gr, green tip, and ADCOM M855. All cartridges performed roughly the same. The best group I was able to shoot was just under 5 inches. I have e-mailed DPMS with this issue and hopefully they will help me out even though I lost my reciept. Maybe they know what the issue might be or have me send it in for evaluation. I have never dealt with DPMS and don't know how good their customer service is. Maybe some of you could chime in. I know the general concensus is that the barrel has a problem and you all may be right. I just figure I would let DPMS figure it out before I invest any more money in the rifle.
Here is one group of 20 rounds slow fire using PMC Bronze 55gr fmj. I was absolutely frustrated as the other groups looked the about the same. This was shot at 100 yards. and it was very calm today, just cold.
http://i184.photobucket.com/albums/x191/jmg8550/AR15group.jpg
Wow! Barring any human error, I would say something is wrong with the barrel. Look at the bright side, you can shoot around corners with that thing. If DPMS doesn't figure it out, call me. I have an extra barrel, I'll help you out.
Great-Kazoo
12-19-2010, 09:15
pm -em, or if this is who i think it is, call me and i will take a look at it for you.
We can head out to the range and run it through it's paces while having an extra pair of eyes on it and spot for you. Myself, i practice COM and your groups are good enough for stopping a threat.
I really appreciate the offer and the help RARGUNS. I am gonna take you up on that offer if DPMS isn't willing to help. It will be after the new year however. And jim, I am who you think. You can look at it as well. Multiple opinions doesn't hurt.
BPTactical
12-19-2010, 11:11
Is this a factory complete DPMS rifle? From the grouping and erratic nature it appears the barrel may dancing around. FWIW I have pulled barrels off of DPMS rifles and the barrel nut was finger tight!
Check the simple things before you get too crazy. Holding the rifle very firmly(a helper is a nice thing) grab the FSB and try to rotate/twist it. If you detect any movement check the bbl nut. It should be torqued to 40 ft lbs and if needed tighten additionally to line up for the gas tube. Do not exceed 80 ft lbs.
I would re-install the barrel, checking fit of barrel to receiver and the square of the mating surface on the front of the receiver to barrel.
I would also pull the FH and check condition of the muzzle/crown. If it is the least but questionable I would re-crown it.
If you want I am about a 25 minute drive and for me to check it out and correct the issues I mentioned it would cost you less than shipping it to DPMS.
The rifle is a DPMS complete upper on a Rock River complete lower. Here is a pic of the rifle with iron sights:
http://i184.photobucket.com/albums/x191/jmg8550/AR15group001.jpg
How does one check the barrel nut? I know nothing about taking apart AR15's beyond what is required to clean them. The muzzle crown has been checked by a gunsmith at Rocky Montain Shooters supply. It was in good condition. I'll let you all know what DPMS has to say and whether they will ship it back on their dime. I know Springfield would pay to ship their firearms back under warranty.
Great-Kazoo
12-19-2010, 14:48
The rifle is a DPMS complete upper on a Rock River complete lower. Here is a pic of the rifle with iron sights:
http://i184.photobucket.com/albums/x191/jmg8550/AR15group001.jpg
How does one check the barrel nut? I know nothing about taking apart AR15's beyond what is required to clean them. The muzzle crown has been checked by a gunsmith at Rocky Montain Shooters supply. It was in good condition. I'll let you all know what DPMS has to say and whether they will ship it back on their dime. I know Springfield would pay to ship their firearms back under warranty.
i'll call you later. we can toss it on the bench and recheck torque etc.
DPMS replied to my email today. They instructed me to send the upper in. They also think it may be the barrel. I'll keep you all posted when I get results from them. I'll probably send it in mid January.
Why wait? It's their money.
I'm curious as to what it is.
I have to ship it at my expense there. They will probably pay to ship it back. I still don't know if they will cover it under warranty as I cannot fid my reciept. Hopefully they will take care of it.
DPMS called yesterday and told me they are hoping to test my upper this coming week. It is very cold up there and the range is outdoors. He said 35 below, I can understand a delay. Should have it back soon though. Great customer service so far.
I'm betting on the front sight or the barrel nut being loose.
We goofed around with it a while back and the front sight base was loose and would wiggle from left to right. That does not explain the groups it puts on paper. If you look at the target JMG8550 posted it has decent grouping from right to left but not up and down.
Curious to see what the problem is
Byte Stryke
01-22-2011, 08:13
as am I
I have had little/No problems with my DPMS.
99.9% of my accuracy issues are shooter related
I Would like to have seen a Target/card with the weapon fired from a sled/rest.
Nothing against OP but I find that they remove allot of the "variables".
I have no access to a sled otherwise thatwould have been my next step. I am a pretty good shot prone though. I can put a sub moa group at 100 yards with my M1A prone and slinged up.
as am I
I have had little/No problems with my DPMS.
99.9% of my accuracy issues are shooter related
I Would like to have seen a Target/card with the weapon fired from a sled/rest.
Nothing against OP but I find that they remove allot of the "variables".
I can vouch for him. He can shoot better than me most times.......but thats ONLY because he has a super match m1a [Tooth]
5moa groups for him is not normal. I would bet 20 bucks it the rifle in some way, shape or form.
Well my upper is in the mail being sent back as we speak, they said it had no problems and they tested it with 69 grain match ammo from Federal and Remington. Hopefully they included a target. They also said that 55 grain bullets are too light for a 1-9 twist barrel and I should shoot no less than 62 grain pills. Is this really true? It is a 16 inch barrel with a standard M4 hand guard. They didn't say how well it grouped. I should receive it Monday. It's about time though, they've had it since the beginning of January. I understand it has been cold, but this long to get it back? Springfield's turn around time has been 3 weeks tops for me, and I've sent stuff to them 3 times so far for various work to be done.
I hate to tell you this but they are wrong about the twist rate. It's the opposite. A 1:9 should work better with a 55g than a 62g. A 1:7 would be better for a 62g.
jerrymrc
03-21-2011, 10:48
I have no access to a sled otherwise thatwould have been my next step. I am a pretty good shot prone though. I can put a sub moa group at 100 yards with my M1A prone and slinged up.
I have one AR that is getting better but I know how ya feel. I sometimes go back to what I call my sanity check gun. If the groups come back with it then I know it is the gun and not me.
I am not any kind of match shooter like some friends of mine but I do ok fighting the NRA HP targets. I also like a challenge so my poison of choice is a FAL. I have one that has turned out to be a 2.5 moa shooter if I do my part. :)
On another note my latest AR has a 1-9 barrel and seems to shoot the 55gr as well as the 62's. It was more sensitive to length than load.
Great-Kazoo
03-22-2011, 22:22
Well my upper is in the mail being sent back as we speak, they said it had no problems and they tested it with 69 grain match ammo from Federal and Remington. Hopefully they included a target. They also said that 55 grain bullets are too light for a 1-9 twist barrel and I should shoot no less than 62 grain pills. Is this really true? It is a 16 inch barrel with a standard M4 hand guard. They didn't say how well it grouped. I should receive it Monday. It's about time though, they've had it since the beginning of January. I understand it has been cold, but this long to get it back? Springfield's turn around time has been 3 weeks tops for me, and I've sent stuff to them 3 times so far for various work to be done.
i have a few different brands of 55gr. swing by the house and i'll put a shooters ammo box together for you. my SBR and the spouses ar shoot 55gr great and both 1:9 .
i found the 55 and lighter ammo say 52gr's really shine in my 20" 1:12
As stated above, the real formula concerns length not weight. But longer slugs are generally heavier which require a faster twist rate.
YammyMonkey
03-23-2011, 21:27
With the vertical stringing the first thing that came to mind was inconsistent pressure or the bipod. Have you tried shooting it off a soft rest with minimal pressure on the handguard? Pressure on a standerd forend will definitely change your POI.
Also could be bouncing around a little on a hard surface, but I'd expect to see less of a consistency in the shots with that.
Byte Stryke
03-23-2011, 21:53
With the vertical stringing the first thing that came to mind was inconsistent pressure or the bipod. Have you tried shooting it off a soft rest with minimal pressure on the handguard? Pressure on a standerd forend will definitely change your POI.
Also could be bouncing around a little on a hard surface, but I'd expect to see less of a consistency in the shots with that.
another reason I suggested a sled.
I have tried shooting groups resting the rifle fore end on a rest with similar results. I have not had a chance to test it with the ammo DPMS suggested yet. I will pick up some match grade ammo and see what happens.
You said you already did this, but here is an article you may find some what relevant.
http://www.theboxotruth.com/docs/bot51.htm
ldmaster
03-24-2011, 09:22
I once had an inaccurate rifle, along the lines of what is frustrating you.
Spent a lot of time on it.
Finally I realized that I was investing lots of time and stress in a 400 dollar problem. So I sold it, bought a new one - problem solved.
I used to be obsessive about getting my guns to shoot well for me, I still am, but realize that my time is worth something and some guns are just money pits.
If you've ever seen a barrel made, you probably know that a lot of it is done by hand, barrel blanks that have been bored and rifled are NOT 100 percent straight, they have to be straightened by an experienced barrel tuner. Then checked with a couple of instruments. Sometimes the tuner messes up.
Things you might want to check:
1. Your barrel crown. Even though you have a FH on it, it might have a few nicks in it (use a jewlers loupe and see if your lands and grooves are concentric and even. this is the most common problem with barrel inaccuracy, and nobody ever seems to check it.
2. Any torque placed on the barrel from the gas block interface with the handguards? Take the hanguards off to check. Think of it as a cheap free float!
3. Swap bolts with any other AR and see if you get the same results. We'd all like to think our bolts are true and mate 100 percent, but that's not always the case.
4. If you're handloading, drop velocity to 2700 at the muzzle. Sometimes the powder/primer/case/bullet combination is just wrong for YOUR gun. I was hugely frustrated with the accuracy of 40S&W ammo when it first came out (remember it's a neutered 10mm) and all the loadings were 180gr for practice. So I worked up a 155 gr load with alliant power pistol and small rifle primers. Worked very well and became a pet load of a local agency that used to reload their stuff for practice.
But personally, I'd just sell the thing if it isn't working well. DPMS PROBABLY swapped your barrel out, which may have done the trick. They don't waste a whole lot of time on this stuff, they just replace things until it works well and get it out.
DPMS didn't replace anything. They test fired it and sent it back with a copy of the target. It really liked Federal Match 69gr.
Here is a picture of their target:
http://i184.photobucket.com/albums/x191/jmg8550/DPMSgroup.jpg
buckshotbarlow
03-27-2011, 16:38
i had the same issue with a bad shooting 308 from savage. Once i found the chamber depth, and seated the bullet just touching the lands it went from 1moa to .5moa just like that. Try finding the land depth, then seat just off the lands and work forward to the lands. It might turn your gun into a single shooter though...
Anyone notice the date on the target. I was just walking by it on the counter in my apt. and saw the date on the target is 8/20/2011. WTF? that date hasn't even passed yet. Also, why is the target a photocopy? They couldn't send the real one? [Bang]
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