Ok, I've finally made a decision on my first AR build. I've been toying around with various calibers (don't really need another .223 - but wanted to build an AR from the ground up..) .22LR, .458 SOCOM, 9mm... All have pros and cons: ammo cost, interchangeability of parts, fun to shoot, practicality... I've collected all the parts for a complete lower, and was just holding out on upper parts until I made a decision. Today, I committed. I found a Grendel 16" Lothar Walther w/ bolt. Let the building begin... As always, any advise from you Grendel folks would be much appreciated!