OK guys, here's the situation, I'm buying an AR A3 upper at a good price. I need to know what brand of lower you all prefer. The upper is an Olmpic arms 16" bull barrel. I'm going to buy another bolt and carrier, and lower receiver. I'd like to get a match trigger if possible. What brand to buy? Or should I just buy a stripped lower and build myself? Are AR lower internals all dropins? Please advise. Thanks.