You've probably all heard this before, but I'm building my first AR15, so let me apologize in advance. I'm interested in a precision type with a emphasis on minimizing size and using as many polymer parts as possible to keep weight down. Outside of that, a 1911 style grip and using the standard 5.56 caliber are my only preferences. I know all fashions of pistols, but rifle...not so much, so I need some help on picking brands. Thanks in advance.