I recently picked up a 10" URX 4 for my 10.3" SBR; i didn't do much research prior to purchase and while i like the design and proposed durability of the one piece design, i've been less than succesful with  proper gas block alignment since it has to be installed after the rail is installed and since the gas block is inside the rail.

Any pointers/tricks/tips??

Pretty easy if using a set screw gas block and dimpled barrel. Almost impossible if using taper pins without milling slots or holes for the pins.

Make sure gas tube is lined up correctly with rail off. Dimple your barrel in correct spot. Put it together. You should be able to access the the set-screws through the KM holes on the bottom of the rail. Make sure threads are clean on threads of GB and set-screws. Use Rocksett on screws.

*Do not attempt to remove set-screws without first soaking in water. I usually fill a bucket up and stand my rifle in it muzzle down. I let it sit overnight. Screws come right out the next day. If you try removing set-screws with Rocksett without soaking, you will strip the Allen head out and you'll be fucked.

The URX4 is a great rail but it is not an easy install. Take your time and plan ahead. I have mine with my GB pinned. I put my gas tube in last. Figure that one out!

Thanks guys. I tried multiple minor adjustments for alignment and then just removed the rail and started over today.  I recently had the 10.3" barrel cut down from 16" and i opened up the gas port from .070 to .078.  i'm not sure if that was the issue but i reassembled the upper with just a GI barrel nut and no rail; i ran 4 mags of 4 rounds each through it with no issues (i ran nearly empty mags to ensure mag lock back).  I went as far as to outline the gas block in pencil to use as a guide when i get the urx back on and have to install the gas block.  Its a bcm barrel and has one dimple but its a wide, shallow dimple that isn't a precise alignment for a set screw as i'm used to.  Hopefully all of this ensures 100% function so we will see.  

I love the one piece design and the price isn't too bad compared to most KAC items. Hopefully i get her up and running this week.