Is my barrel off or is it the receiver?

[UTShooter71]

The handguard appears to be straight. It is the barrel that is off kilter.

[TonyAngel]

Okay, so just to see if it was the cheap handguard that I picked up I bought a new set. This is a Matrix Arms free-float. When I just set the barrel into the upper it lines up perfectly. When I hand tighten the barrel nut it stays lined up perfectly. After I torque the barrel nut down the barrel still points right, visibly out of center inside the free-float handguard. I don't know what to do. Is it the barrel, where would I look for something to be "off"? Is it the upper? Maybe I just didn't notice it with the Troy handguard.

Man, I misread this post. So, all is ok until you torque the barrel nut down. And you're sure it's the barrel that's off and not the handguard? How tightly did the barrel extension fit into the upper?

I don't think I'm understanding the origins of the parts either. Did you have a complete upper from Palmetto and are replacing the handguard or did you order an upper and barrel from PSA and are assembling them?

I take it that at some point, the barrel was installed in the upper with the Troy handguard and all was well? Did you have any problems getting the Troy handguard off? Did you use the proper fixture to remove it?

I've worked on a couple of uppers from Palmetto that involved the use of a torch and pipe wrench to get them apart. If all was well before you pulled the Troy handguard off, something has changed since then.

Pictures of the barrel extension and upper with the barrel removed might help. How does the barrel fit into the upper now? Is it a tight fit or is it really looose? Have you actually removed the barrel from the upper or just replaced the barrel nut?

When you pulled the Troy handguard off, you didn't find anything like half of a barrel shim in there, did you? Or maybe something between the barrel extension and the face of the upper?

[Core781]

Why did you replace the Troy with a unknown Chinese hand-guard? Sounds like the answer to me. Return it and get a American made fore-end. I doubt the PSA upper is out of spec but anything is possible: that said doubtful and can be easily determined. Take everything apart, and check the upper's extension face for tolerance. Just lay it on a quality made clear pane of glass and it should seal all the way around with no gaps or inspect it visually with a precision rulers straight edge. It will probably be fine and your Chinese hand-guard is shit.

[UTShooter71]

Problem solved. So I checked everything and it was all tried up. The face of the receiver had no irregularities. The barrel extension was the same. So I put it back on and realized that the barrel nut was buttoming out before I could fully torque it down. After taking it apart again I added the thickest barrel nut shim I had; .007(?).

This was enough. I got it to torque down at 35 pounds and the barrel is properly centered in the free floating handguard. I cannot describe what a relief it is to be done. Now to sight in the irons and the Vortex red dot.

[UTShooter71]

Why did you replace the Troy with a unknown Chinese hand-guard? Sounds like the answer to me. Return it and get a American made fore-end. I doubt the PSA upper is out of spec but anything is possible: that said doubtful and can be easily determined. Take everything apart, and check the upper's extension face for tolerance. Just lay it on a quality made clear pane of glass and it should seal all the way around with no gaps or inspect it visually with a precision rulers straight edge. It will probably be fine and your Chinese hand-guard is shit.

My son in law has the original handguard. If I had any idea how much of a nuisance this was going to be it wouldn't have happened but the Matrix Arms handguard is great.

[Core781]

I picked up a German hand guard and had the same issue. From now on I’m just buying from a reputable US company. The good aspect of this handguard was the high strength steel barrel nut and it locked up well with very little movement on the barrel nut.

[UTShooter71]

What distance did you zero at? Also, it should be noted that rails that have very little surface contact with a barrel nut, like the troy alpha for instance can easily be forced to one side. Some rails can even develop an upwards cant if the bottom clamping mechanism is over torqued. i used to see this on Samson Evo rails.

Hello,

I have taken to zeroing most (all) of my rifles iron sights at 50 yards. I believe that this is standard now for most AR-15/5.56 rifles as a standard rifle of this type provides for the least deviation in point of aim/point of impact from 0 - 200 yards. I don't know exactly how true this is but it does work for me. Anything that has a magnified optic is sighted in at a different range but red dots are also sighted in at 50 yards.

I believe you about the rails as well though this is the first time in building a rifle that I have run across this. It will be something I really look for on future builds.

Thank you