Initial run nightmare - suggestions please!

[6.5dg]

Put together a new rifle and was not pleased with the groups when i finally got around to testing the rifle for the first time. If i had to characterize the grouping, only word that comes to mind is random. All within 7 inches but completely random.

AR Stoner barrel, ASA side charge upper. The two did not come together with a very tight fit so i used blue lock tite to bed together. Used a torque wrench around 60 lbs.

Zeiss scope with Larue mount, very tight and no movement.

Firing is flawless, brass does not show any signs that would raise an eyebrow.

Looking for suggestions on steps i should take to improve. Thought i would start with putting a wrench to the barrel nut and tighten to next slot?

[mongoosesnipe]

there have been a few dud barrels sporting the stoner name cheek the crown for defects bout all you can cheek without specialized equipment other than that your not free floated so putting pressure on the fore-end puts pressure on the barrel try a freehand group instead of off bench

[LRRPF52]

What load?

Brass:
Primer:
Powder:
Charge weight:
COAL:

60ft-lbs is plenty for the AR15 barrel nut. DO not try to go to the next tooth slot on the barrel nut, as you could possibly exceed 80ft-lbs and compress your receiver face & threads.

Even with the gun not free-floated, it shouldn't be shooting that erratically, but it doesn't surprise me considering the barrel source. Some of those AR-Stoner barrels have worked out great for people, and others not so much. 7" groups at 100yds is about twice the acceptable standard for a mass-produced military rifle.

I have an economy barrel from AA that cost under $270 with the bolt, and it shoots anywhere from .79"-1.1" at 100yds, and 1.69"-2.18" at 200yds with factory ammunition. It is very consistent in that regard. Bwild97 has a 24" J&T upper with a button-rifled economy barrel that shoots 10rd groups into sub-1/2 MOA, with several different loads, and he has page after page of excellent accuracy results with that rifle and probably the widest variety of loads shot on the forum.

Most Grendel owners are disappointed if their rifles don't shoot at least 1 MOA at 100yds.

[Variable]

Put together a new rifle and was not pleased with the groups when i finally got around to testing the rifle for the first time. If i had to characterize the grouping, only word that comes to mind is random. All within 7 inches but completely random.

AR Stoner barrel, ASA side charge upper. The two did not come together with a very tight fit so i used blue lock tite to bed together. Used a torque wrench around 60 lbs.

Zeiss scope with Larue mount, very tight and no movement.

Firing is flawless, brass does not show any signs that would raise an eyebrow.

Looking for suggestions on steps i should take to improve. Thought i would start with putting a wrench to the barrel nut and tighten to next slot?

One slightly possible thing (and it's a long shot). You mentioned you are using a Larue mount... Is it possible that you didn't fully tighten the bottom of the ring halves before you started to tighten the tops? I say that because if you didn't fully tighten the bottoms first (thus locking the rings to the base) you could have tight rings that can actually move on the base... Again, it's a long shot, but I'm aware of one dummy that did that (me ) while distracted and in a hurry one time.LOL!!!

[stokesrj]

There are any number of things that could result in what you are now seeing. The most likely culprit excluding the barrel is the gas tube. If you did not make sure it had free movement from the gas block to the receiver equal sides of the center line of the barrel, that could result in what your are seeing. The gas tube has to be aligned properly or it can heat up and introduce harmonic changing forces to the barrel and action.
As others have mentioned I would look at the crown first, throat second, in between has almost no effect.
Bob

[rickOshay]

Going along with what Variable said - how does it shoot with the iron sights?

[6.5dg]

I will try and answer all recommendations. Ammo used was Hornady 123 grain factory loaded and 120 grain Wolf factory loaded. Equal results.
Used a folding front sight/gas block to go with the theme of the rifle, shoot with it folded down. Built this rifle to hunt with, never intended to use iron sights.

Spent a lot of time locking down Larue mount to scope...

Gas tube seems right, looked through scope in garage tonight with front sight up, and while gripping hand guard the blurry image of the front sight would move left/right of the verticle crosshair?
clue?

[Variable]

...and while gripping hand guard the blurry image of the front sight would move left/right of the verticle crosshair?
clue?

Not really. If you mean the front sight appears to move in the optic as you move your head around, then no. That's caused by parallax.

[6.5dg]

Head still and crosshairs fixed on a spot on the wall.

[6.5dg]

ar3.jpggroup51a.jpgProblem solved! Yankee hill free float tube ordered and installed brought the groups back to my expectations. Target shown 6 shots @ 100yds with Hornady amax ammo. Never shot long range so i am going to give 500 a try this weekend. Scope has a rapid z 600 recticle and i am curious how effective it is.

[LRRPF52]

So the non-floated handguard was enough to make 7" groups, and free-floating shrunk the groups to around 3/4" or less. That's a huge improvement in accuracy. Any plans for the wood handguards?

[6.5dg]

First build and i really struggled with the old style barrel nut. Most likely operator error on the first attempt. When i removed the handguard, the notch that fit around the barrel nut broke on both halves. Reduced to firewood now i guess.

[LRRPF52]

First build and i really struggled with the old style barrel nut. Most likely operator error on the first attempt. When i removed the handguard, the notch that fit around the barrel nut broke on both halves. Reduced to firewood now i guess.

Noooo! It can be salvaged for a retro project. Send them to me if you intend to toss them.

[LRRPF52]

PM sent

[Keep The Change]

I'm confused how these handguards could cause this. Those hand guards were putting enough pressure on the barrel to move impact points 7" and then varies upon on subsequent shots.

Can you explain what was broke when you took the hand guard off? Was it the Delta Ring?

Now I'm nervous about using a delta ring and my Vltor CASV hand guard. Although the Vltor setup doesn't attach at the gas block. It attaches to the delta ring and the rail on the flat top upper.