AR accuracy issues

[jmg8550]

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?

[275RLTW]

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.

[jmg8550]

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]

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?

[esaabye]

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.

[275RLTW]

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]

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

Hope the kids feel better before Satan Claws comes

[jmg8550]

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.

[RARGUNS]

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]

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.