Colt 6920 & KAC RAS installation difficulties

[MartinBrody]

My friend bought a new Colt 6920 and a KAC RAS and we can't get the thing on. We have the handguard takedown tool and removed not just loosened the screw on top of the rail and we just can't get the thing on. We are orienting the rail correctly and the bottom piece goes right on, but the top won't slip under the delta ring.

It is his rifle but it is aggravating me now. From everything I have read the KAC is authentic. From what I can tell the 6920 and the RAS should work, any advice?

[Guns4Fun]

I'm not exactly sure about the KAC RAS but i do know that the MI railed handguards have 2 different part numbers. One for colt one for non colt.

Here is the info from Bravo Co.

Please Note: There are currently two Carbine #17 models available. Because Colt uses a slightly different shaped handguard cap, there is a model #17 for carbine uppers other than Colt, and a model #17C for Colt carbine uppers.
If your upper is not a Colt product, please order a MI#17.
If your upper is a Colt product, please order a MI#17C.