Hello,  Im new to this forum and new to the Ar 15 world....I've been doing some research on what AR to buy and based on what I can afford and what I've been reading I think I'm going to go w/ a BCM Mid 16.  QUESTION:  I eventually would like to have the best BCM that you can build but can only afford $1200 right now.  Should I buy the basic BCM now or get the MOD 2 and add as I go?  From a barrel stand point, does the MOD 2 come w a good barrel or should  I plan on changing that as I aquire funds?  Also, I like the BCM edition Troy battle sights....how hard is it to change the front sight of the MOD 2?  Thanks for any help?