So with my new AR-15 build being a 6.5 Grendel and just got into reloading, I have been reading on sectional density and ballistic coefficient. I have never really been curious about it until now because I have never really had the need. From my understanding if I am correct BC is related to the bullet ability to overcome air resistance the higher the BC the better or from what I have read the "slicker" the bullet. But the sectional density is what I am having trouble comprehending. When does this matter? When does it matter to apply towards game such as coyotes, deer, elk, etc? (speaking in general not this particular cartridge) I eventually want to start poking out to 400+ yards and and experiment with shooting long range...