I'm trying to set up my CHTF/zombie AR-15. 16" A3 flattop with a standard FSB and a fixed rear sight for the maximum durability and reliability. If the EoTech fails, irons always on. Thinking about installing a carbine-length free float tube for accessories and that theoretical accuracy. Question One: Must serious rifles have pinned on gas blocks? I'm hearing that if my gas block is going to be outside of my forearm, that it is best to pin it. Just have not seen any pinned gas blocks (in person). Being told that the supplied set screws still are subject to impact and movement. For example, would this YHM flip up front sight really come loose to the point I shouldn't mount on a SD rifle? Or this Stag gas block? Anyone rockin this on their zombie rifle? Question Two: Are people mounting YHM flip up front sights or other flip sights on their free float rails on their home defense rifles? Rifle could be used for SD but most likely more range time. What does the tribe say?