Originally Posted By alpha0815:
Good info, thanks.
Im about to start a build with ARFCOM billet receivers and think the URX4 is best bet. Going with 11.5” barrel, so will probably opt for 10” handguard. I wonder if ADCO would do the work for me. Honestly I’d rather pin the gas block vs just set screw / dimple.
I'd go with a 10.75" URX4 MLOK. There is no more appropriate handguard length when using an 11.5" barrel than a 10.75", IMO. Gives you just a bit more room over the 10", and makes for an absolutely killer looking setup.
As far as ADCO doing the work, I'm sure they would, and if you're set on having the block pinned then maybe they are your best bet if you don't have access to a pinning jig. I can say that the URX4/SOCOM barreled upper I mentioned in my previous post has seen some pretty rough service and has a decent round count on it using a set screwed block and I've not had any issues with it. Same with countless other uppers I've assembled for myself, friends, and customers, but I understand it's a personal preference thing when choosing your method of gas block attachment.
I'm not sure what your skill level is or what your tool selection looks like, but I would prefer to do it myself. Installing a URX4 isn't as complicated as some make it out to be. Sure, there are some differences between it, and a handguard using a traditional barrel nut, but it's still very easy.