BCM has 16in. light weight, mid length in stock right now. It comes without hand guards and bcg/charging handle.
Which yhm free float can just have rails added and will i have to remove the fixed front sight because thats a option i don't want to part with
The YHM FF smooth/customizable handguards #s YHM-9430A (specter length), YHM-9431A (carbine length), and YHM-9432A (rifle length) are the models that let you place rail section wherever you want. Sadly, their website doesn't list a mid-length model, so if you want to keep your FSB, those are a no-go. If they do make a middy model, and they just don't have it listed on their website, then you can go with it.
YHM does sell another smoothish FF hg, but these have rails that are machined onto the tube and are not moveable/customizable. They do offer this one in a mid length (# YHM-5004A)
I have two YHM FF lightweight handguards on uppers right now; one middy and one rifle. For the dinkin' around that I do, they work well. They were affordable, installation was simple (though I did not have a FSB to contend with), and they do what they are supposed to do - FF the barrel. BUT - and this is just something to think about - unless YHM is doing something different these days, their FF handguards utilize anti-rotation screws that lock into the barrel nut. Basically, the only way you're going to rotate the handguard is if you apply enough torque to rotate the barrel nut. I haven't had a problem with mine, but I don't 'run and gun' with mine. But, I guess the possibility exists that the handguard could rotate on you if the barrel nut wasn't torqued properly. If you install the YHM handguard yourself, or have it installed by a competent person/smith, you can vastly reduce the chances of this happening.
That said, if you plan on a lot of hard-charging, heavy-duty, nitty-gritty, diving-out-of-moving-vehicles type manuevers, perhaps consider a free-floated handguard that has some sort of anti-rotation system that ties into(onto) the upper receiver somehow.
If you want a middy upper and want to go with a FF handguard and still keep the FSB, your choices are:
-to get DD handguard that has the FSB cutout at the middy location (if you want some 'railestate' to extend past the standard middy hg length)
-you need to get a middy-length FF tube.
Whatever you decide on, remember that the AR platform is modular, and you can change things up down the road if you need/want/can afford to.