Any help would be awesome...  Its the full size 5/8 24 for 300 blk.  Its pinned to a 14.5 barrel...  So obviously the handguard needs to slide over it...  I am thinking ALG Defense but I also like the size of the UTG slim but cant find dimensions on it.

the barrel isn't pinned yet...  I am starting to put it together tomorrow and I have access to most rails at a dealer in town...  I will slide the barrel nut on the gas block then pin the flash can.  I need the rail to slide over the can.

What barrel nut is already on the barrel?

The barrel nut will limit you more than the handguard.

The hard part will be the barrel nut not the handguard.
What do you have on it now?

ETA: 15 seconds, lol

Its not pinned yet.  The plan is to slide the nut on then the gas block then pin and weld the comp so the rail will slide over it all.

Oh, ok. We were just responding to your first post that said it was already pinned.

There are haters out there but I really like the SS handguard. USA made too.

Completely agree on the hater part but it is what it is.  I held the slim 15 and the ALG for 10 more dollars the ALG Defense V1 felt like it weighed a good pound less than the UTG so I went with that.  Took my comp with me and put it down both.  Its snug but works they let me mount it on a stripped upper and tossed a barrel on with it they were just as curious as I was which was cool as heck as well.  But they only had a 10.5" barrel so if it went on over that I was good period...   Gotta say I love the look of no 1913 rails anywhere on this handguard and if it works well I may slap it on my other ARs as light as it is.  My wife hates the weight of hers all the time but its a carbine with pencil barrel and feels stupid light to me so...