I recently bought a smith and wesson m&p 15 sport 2. I've also ordered a magpul MOE rifle length drop in handguard. What modifications do I have to do to the gas tube in order for this to work. I know I'll have to move the iron sight to the length where the new handguard will drop in. Do I have to get a new low profile receiver for the gas tube? Because right now its tieing into the front iron sight. Will this work? What can I do? Is it possible or should I just take it back and stick with the carbine length, wich I didn't want... thanks in advance if you can help me.