Hi all. I have an inexpensive 16" AR upper that is shooting large-sized groups (3-4") at 25 yards from the bench. I know, you get what you pay for, but I've used cheap uppers before with much better results.

I've had several others shoot it to verify that it wasn't me, and I've used a variety of optics including iron sights. I've also used multiple brands of ammunition in various bullet weights.

I have built several AR lowers, but I always buy my uppers assembled. Is there anything (other than a crap barrel) that could be causing the accuracy issues? Is there something that I can check to find the cause?

Any help would be appreciated.

quote:

Originally posted by Maestro:
Hi all. I have an inexpensive 16" AR upper that is shooting large-sized groups (3-4") at 25 yards from the bench. I know, you get what you pay for, but I've used cheap uppers before with much better results.

I've had several others shoot it to verify that it wasn't me, and I've used a variety of optics including iron sights. I've also used multiple brands of ammunition in various bullet weights.

I have built several AR lowers, but I always buy my uppers assembled. Is there anything (other than a crap barrel) that could be causing the accuracy issues? Is there something that I can check to find the cause?

Any help would be appreciated.

How's the crown look?

Are the bullets getting gouged/scratched up badly as they're being chambered?

Any damage inside the barrel? ( Metal shard, etc, hanging down from the gas port. )

Is the barrel tight with the upper itself?

Who's upper/barrel is it?

I can only guess that maybe the barrel nut is loose and letting the barrel wiggle some? Or just a really terribly rifled barrel?

How's the crown look? The crown looks fine- nothing out of the ordinary.

Are the bullets getting gouged/scratched up badly as they're being chambered? No

Any damage inside the barrel? ( Metal shard, etc, hanging down from the gas port. ) Not that I can see.

Is the barrel tight with the upper itself? I think so....is this obvious th check?

Who's upper/barrel is it? Not sure of the manufacturer of the upper receiver, but supposedly the barrel is made by FN.

quote:

Originally posted by Maestro:

Who's upper/barrel is it? Not sure of the manufacturer of the upper receiver, but supposedly the barrel is made by FN.

Sounds like a Palmetto Upper possibly?

It might be a Palmetto. It was a gun show upper.

I took the hand guard off and the barrel nut seems tight, and the barrel isn't moving a bit.

FN has a rep of making great barrels. 3-4 inch groups at 25 yards is insanely bad. I'd have a competent gunsmith look at it.

quote:

Originally posted by Maestro:
It might be a Palmetto. It was a gun show upper.

I took the hand guard off and the barrel nut seems tight, and the barrel isn't moving a bit.

Does the barrel have a nitrite finish or is Stainless? Any markings on the barrel?

Going from memory I think my FN PSA barrel was marked: 1/7 .223 CHF CL Or something of the sort.

Nitrite finish, only marking is the 1/8 twist, and it's an M4 profile. There's no CHF marking on this barrel like my PSA.

quote:

Originally posted by Maestro:
I took the hand guard off and the barrel nut seems tight, and the barrel isn't moving a bit.

That answers my first question. We had an officer with a Colt AR and during a qualification he suddenly started shooting shotgun patterns rather than groups. I first thought (rather uncharitably, I admit) he’d fallen apart under the cold, low-light conditions, but the accuracy was so bad that that didn’t seem reasonable even for him, and I tested it myself. After checking everything else I could think of, I checked the barrel and the muzzle would move a good quarter inch. He ended up having to replace the upper because it was damaged by the barrel movement.

Since you’ve ruled out a loose barrel, I can only think that the barrel has some sort of major issue such as being oversized.

If it were me. I'd probably order a Ballistic Advantage, or Faxon barrel for it. Throw it on and I bet that'd fix any issues.

heck at my indoor range you would be an ace expert plus super master champion ar shooter with groups 3-4 inches at 25yds.

all kidding a side. what sights? how are they fixed on, are they properly torqued down to the inch pounds. Do the small parts of the sights wiggle when moved with a finger. Years ago on my sig 556 patrol swat their rear sight diamond would wiggle like a stripper at a dock workers convention. Tightened it up, the groups shrank significantly.

After the sight, the first thing i would do, is loosen the barrel nut, and remove the barrel, clean it, put it back in, and properly re-torque the whole shebang. Over torqued or under could be the cause.

DOES anything else wiggle and wobble? I have see horrible non mil spec uppers or lowers throw off horrible groups. So if nothing wiggles or wobbles. and the groups do not shrink with a good scope on a bag. Then check every other measurement on the screw, nut, fastener, pin and spring ect.

Finally how is the trigger. When people go from their 2lb timminey uber ectrontic brainwave activated trigger to a stock trigger groups do tend to blow a bit up.

So, does it have a muzzle device of some kind? Was it tight? Did you take it off to inspect the crown?

If it has a muzzle device of some kind check that it's bore is in line with the bore of the barrel.

Take it off, inspect the crown, look closely in good light. It should be symmetric, no scratches or especially gouges. Use a very soft, fuzzy cloth and see if any small burs don't pull any fuzz off.

Make sure the barrel and index pin is fully seated with the upper receiver.

Make sure that your gas tube is seating into the gas key without interference, is there odd wear on one side of the gas key?

ARman

quote:

Originally posted by ARman:
So, does it have a muzzle device of some kind? Was it tight? Did you take it off to inspect the crown?

If it has a muzzle device of some kind check that it's bore is in line with the bore of the barrel.

Take it off, inspect the crown, look closely in good light. It should be symmetric, no scratches or especially gouges. Use a very soft, fuzzy cloth and see if any small burs don't pull any fuzz off.

Make sure the barrel and index pin is fully seated with the upper receiver.

Make sure that your gas tube is seating into the gas key without interference, is there odd wear on one side of the gas key?

ARman

The gas tube was sitting a little crooked...I lined it up. Could that really affect accuracy? I thought that if something was off with the gas tube, it would affect function, not accuracy...but I'm fairly new to AR's...

There isn't any kind of fancy muzzle device other than a standard flash hider.

Have you shot it without the muzzle device?
I would before I'd go ordering another barrel.

If it's a crap barrel it's a crap barrel.
But I like to eliminate every possible cause before opening my wallet.

Gas tube not being properly installed might cause issues but given the distance shouldn't have that much of an influence on accuracy, IMO.

Sounds to me like the barrel is under/over torqued, the upper receiver could be misaligned/defective or the sights are loose/defective. 4" at 25 yards is 16" at 100 yards. I've helped people "fix" their cheap upper builds that were shooting 6-8" at 100 yards and it was usually one of those three things that tightened it up.

The only other thing I can think of is using lightweight bullets in a fast twist rate barrel. Have you tried heavier bullets/slower ammo?

Perhaps check the headspace and how the bullet imprints onto the lands of the barrel. Again 4" at 25 yards is really, really bad and I've never had to diagnose something that shot that poorly, all due respect.

If I had to start replacing things I'd start with the barrel (and get a slower twist rate for 5.56/.223) then the upper receiver.

quote:

Originally posted by Dead_Eye:
Gas tube not being properly installed might cause issues but given the distance shouldn't have that much of an influence on accuracy, IMO.

Sounds to me like the barrel is under/over torqued, the upper receiver could be misaligned/defective or the sights are loose/defective. 4" at 25 yards is 16" at 100 yards. I've helped people "fix" their cheap upper builds that were shooting 6-8" at 100 yards and it was usually one of those three things that tightened it up.

The only other thing I can think of is using lightweight bullets in a fast twist rate barrel. Have you tried heavier bullets/slower ammo?

Yes, I've tried several bullet weights. I'm guessing that something isn't torqued correctly. Time to visit a gunsmith.

Probably the best option before you start replacing things. Good luck!

quote:

Originally posted by Maestro:

quote:

Originally posted by Dead_Eye:
Gas tube not being properly installed might cause issues but given the distance shouldn't have that much of an influence on accuracy, IMO.

Sounds to me like the barrel is under/over torqued, the upper receiver could be misaligned/defective or the sights are loose/defective. 4" at 25 yards is 16" at 100 yards. I've helped people "fix" their cheap upper builds that were shooting 6-8" at 100 yards and it was usually one of those three things that tightened it up.

The only other thing I can think of is using lightweight bullets in a fast twist rate barrel. Have you tried heavier bullets/slower ammo?

Yes, I've tried several bullet weights. I'm guessing that something isn't torqued correctly. Time to visit a gunsmith.

Once you get to the gunsmith, ask him to scope the barrel.

My gut call says you've probably got something shady going on in that barrel.

Hopefully though, it's something simple and easy to fix.

quote:

Originally posted by myrottiety:
If it were me. I'd probably order a Ballistic Advantage, or Faxon barrel for it. Throw it on and I bet that'd fix any issues.

This !!
I'm running three Ballistic Advantage barrels on three different AR's. 10.5, 7.5, and 16 inches.
I'm getting great grouping on all three.