I have a CMMG 10.3 with FSB that I want to convert to a FF set up with micro gas block & flip up buis's. I'm looking at either the MI 2-piece FF's or the DD Lite Rail & I'm wanting the business end of the rail to be as close as possible to the aft end of my AAC Phantom FH but still allow clearance for the wrench to be used to tighten the FH. What length will allow the setup I'm looking for? I see that the MI's offer a 10" & mid & the DD Lite Rail offers a 9 & 10" FF. What's the longest length for either that will give me the setup I'm looking for? Better yet, anyone else using the 10.3 in conjunction with either of the rail systems mentioned? TIA.