I like to be prepared to deal with anything while I'm out on the range for a long day of shooting. What would experienced MR762/MR556 owners/operators recommend for a field emergency repair kit for my MR762? I generally like to have an entire spare BCG on hand with my AR 5.56 rifles, but a "spare full BCG" for the MR762 is crazy high price. Any parts that I should have on hand? Most like to go down?