thinking of putting a FF rifle length hanguard on my carbine. its on an A2 and and i was gonna mount a red dot sight on a set of risers on the hand guard area. I've seen some people do it and i really like the rifle handguard on carbine, i suck at iron sights anyways so i was gonna go with no back up sights, but i can always put it on later on the front. bad idea? good idea? i wanted to spend 150-180 ish. i just need a low profile gasblock and a FF hanguard right? or can i cut the FSB?