Next we look at the cam pin “travel” slot. You will notice this slot on the AR to be very short and abrupt when compared to the Scar. The slot on the AR is 0.6440” in full travel length with my well used calipers, and the slot on the Scar is 1.082. That is a drastic increase in the time it takes to unlock the bolt on a Scar versus an AR. One will also notice the slot on the Scar is more gradual in twist. The AR bolt starts to unlock almost immediately when the carrier moves to the rear. The Scar carrier moves almost an entire half inch before the bolt starts to unlock. What does this do? It allows for a little bit longer period of time before the bolt unlocks and removes the spent cartridge. Why is this beneficial? It allows the cartridge more time to cool back down and shrink from its expanded state against the chamber walls.
I think the 7 lug AR bolt and its short cam track is a result of having to use gas rings around the bolt, which is a point of friction.

In order for the expanding gas to be as efficient as possible in cycling the BCG, you design a rotating bolt with the shortest lock/unlock distance.