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

[Colorado Osprey]

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]

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.

[RARGUNS]

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.