[4runnerman]

I weigh my cases after they are deprimed and tumbled. Sorted down to 1 gn difference. I shoot 223 and when i weighed my cases i found out just in 223,they came in from a low of 88 gns to a high of 108 gns. If you throw them all together and load all with same gns of powder they are still not going to group the same. 93 gns was the most common. So i pulled all 93 gns and trashed the rest. Keep in mind this is all bearing on how accurate you want to be and how much your willing to put into it. But as stated earlier,case lenght is by far the most important of them all.

((They'll seat fine even after 2 shots worth of carbon inside the pocket,,))

Seating fine and seating right are not the same thing. One can shoot 20 times and still push a primer into the pocket. Difference i can't say much as i have never tested the theary. I just do it as a part of reloading. Just like cleaning flash hole,never not done it ,to tell you if it makes a difference.