I am in the market to purchase my first AR. I want a fighting rifle that will serve me well if SHTF. After spending hours and hours reading and researching, I originally concluded that I would get an LMT upper in 14.5", an LMT Defender lower with SOPMOD stock, standard trigger, and an ambi-selector (I'm right handed, but left eye dominant), and an LMT standard, full-auto BCG. Since I do not want to register this weapon, I was going to put a Sabre Defence Flash Suppressor on it to bring the total length to 16". After some more thought, however, I'm not sure this would be the best decision. I am now thinking of getting a 16" BCM Mid-length upper and the same LMT lower as above. My thinking is this: If I'm going to have to register a rifle, I want to get my money's worth and go with a 10.5" or 11.5" upper (I may do this later this year or early next year depending on the results of the coming election), but I don't want to get an SBR for my first AR. Having to register your rifle because of 1.5" just doesn't seem worth it to me (maybe I'm wrong, if so please tell me), so, I'd have to permanently attach the flash suppressor, which then limits my rail options in the future. I know I could use the DD Omega, but that's about it, and seeing as I have no experience with rails, limiting myself seems foolish. If I'm going to end up with a 16" anyway, why not purchase a 16" to begin with? That way I could get it in mid-length, which everyone seems to agree is a better system, and I will have more options when it comes to rails. The advantages of the 14.5" over the 16" (some say the former has better balance and is better for CQB) seem negligible, particularly once you factor in the permanent flash suppressor.
With all of that said, I guess my questions are as follows:
- What are your thoughts on the 16" BCM mid-length as opposed to the 14.5" LMT carbine?
- Which BCG would you recommend, BCM or LMT? And, if you recommend LMT, do you recommend the enhanced full-auto or standard full-auto?
- Is there an advantage, in terms of warranty, reliability, etc., in having all LMT parts vs having an BCM upper and possibly BCG on top of an LMT lower?
- What are your thoughts on the ambi-selector?

