Great design but note - FM Products FM-9 AR 9mm Forward Charging Upper Receiver w/ Micro Brake

Ive been looking at this upper on all sites since 2020 with 1 hesitation. The space between the charging handle and top picatinny rail are very close. NOTE my question of whether that space was usable and was answered yes. It is NOT, and is a let down the manufacturer couldnt go 1" further. Other than that I think its top of the line upper that stands out. Fits well on my AR9 80 lower, performs well, and holds open. I Would give it 5* if the unusable space was in the description or the manufacturer seen that issue on a prototype and maybeade adjustments.