Hello all. Long time reader. First time poster. So I am looking to build an ar dmr type build. Was looking to max out at 600-700 yards. So I’ve been a fan of the Hk mr556 upper. I like the build quality and accuracy. However I am a lefty and like a lower with ambi controls built in. In that respect I wanted some outside input. As I have a chance at getting a hk mr556 upper. And was thinking a Daniel defense lower. As the controls are easy to manipulate for my little carnie hands. That or a precision weapons systems ambi lower. Wanted to get input as to compatibility in regards to the buffer system. Has anyone done something similar. Honestly I’m a semi experienced shooter. Have a bunch of ar’s but all direct impingement. Never had a piston gun. So don’t know if my Franken dmr project is viable. Or should I just get the dd mk12 spr upper as well and be done with it. Thanks a bunch. Y’all have a great day.