I've been on bcms website and I was looking at a 16 midlength upper with an 11 inch handguard. Thing is I want a 15 inch handguard and found one on the site. Now the thing is any of the uppers that come minus the handguard have the fixed front sight. What's the deal? Is it easy enough to swap out to a low profile? I saw a vid on YouTube where a guy shaved it down himself is this a good idea?