No need for a steel helment i am in the midst of learning the MOA for a scope rifle combo from 300 yds zero stop to 900yds. In amongst this i think my ammo is going subsonic at or just before 900yds .
400yds = 7MOA , 500yds= 14MOA, 600yds = 23MOA, 700yds = 32MOA? still learning out here. The wind strength and direction can mean +/- .5 of MOA.
When i have finished this one i have a another to learn, L42 type using 308 Palma match ammo because surplus 7.62 is not an option or i build a load to fit the rifle and scope more fun.