I have a Zombie Defense stripped lower on order, should be here first week of May. I am considering putting a 7.62 x 39 upper on the lower I plan to build. Who has experience with AR's in 7.62 x 39? So far I have only found information about Bushmaster and Olympic complete uppers. DPMS lists an upper on their website in 7.62 x 39, but there is no information available yet. Considering the 7.62 x 39 because I already have a 5.56 / 223 and just want to have something different.