I like the MOE handguard but if you need a rail mounted front sight then maybe a quadrail is better.
Bushmaster offers a front sight (actually made by YHM) that clamps on their low gas block. I have seen them on other BMs so take a look since your C15 may have that block. That way you could use the $30 MOE which does a fine job except maybe as a sight mount.
Otherwise, buy lots of ammo and go out shooting!
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together.
US Army 1966-69, VFW Life Member, Retired Geek