Hi all,

I recently gathered the parts to make a quality AR upper (Colt Cage upper, DD barrel, KAC URX 3.1) I had a local gunsmith assemble it for me because I didn't want to have to install the URX 3.1 myself, and now I'm concerned that something is wrong either with the installation or the compatibility of parts. The first thing I noticed was that the barrel seemed a bit off center in the handguard, so I looked down it and, sure enough, the barrel appears to be to the left a bit. The gas block also seems to be cocked left. Then, looking down the 12 o'clock rail, the handguard looks to be ever so slightly twisted. The barrel's interface with the receiver, I do not believe to be the issue, as the feed ramps line up properly. I took it back to the gunsmith and he took out a caliper and confirmed that the barrel was off-center from the handguard. All he said was to try to zero it and tell him if there were issues there. Not exactly thrilled as I was really excited about this upper, and now I'm a bit depressed about it.

I'm wondering if anyone here has experience with these handguards and can offer some input or advice.


Pics for reference: https://imgur.com/a/2eXyQgt

I have installed two of these myself and neither one are misaligned like that.
When installing mine I sanded my upper receiver until it lined up with no gap, so I don't know if that has anything to do with the alignment.
I would email KAC and see what they have to say about it.

Yeah, I just sent KAC an inquiry. We'll see what they say. I'm also reaching out to various reputable KAC gunsmiths to see if I can send out my upper for readjustment.

Unless you mill the aft face of the URX to time with the upper the gap is common. Slightly off center barrels also happen because the barrel nut threads on the upper aren't perfectly square to the receiver. Sometimes things get torqued on install. The canted gas block may be a symptom of the latter.

edit: fixed it, issue with side screws flexing rail for me, but mines modded.