If you were building a new ar15 what parts would you go with? does the stripped lower really matter the name on it or the material its made out of for semiauto?(aluminum vs steel ) is a high end noveske or lmt barrel really worth the money over a colt or armalite or other barrel since most ar15s are set up for 50 to 300 yards? what about rifle twist?55gr is the normal ammo i would use or do you recomend a heavier grain? i know a good balance is important...you dont want too light of bolt for example that wont cycle right for the ammo you will be building. you can use the most expensive parts and if you dont chose the right balance you will have an over priced build that wont shoot right so lets hear your thoughts?