1) Other that the mag block, what required changes are needed on a full auto lower?
2) No gas system used, correct? Thus no front sight/base needed if using a free float tube?
3) Cyclic rate and accuracy and recoil, compared to an MP-5?
Looking at a Rock River kit, any thoughts?
You will need a heavy buffer.......at least run a steel 9mm one or a heavier custom buffer with a M4 stock.
Use good magazines.....Colt is currently the best.