I buy bulk once fired military Lake City brass and below is a trick I learned at our Civilian Marksmanship Program (CMP) reloading forum.
You can ease the sizing effort with machine gun fired brass by first sizing lubed cases with a 30-06 full length die, and then sizing with a *standard .308 die.
A second method is to use a carbide .45 acp die that reduces the case body diameter, without any lube, followed by sizing with a *standard .308 die.
I prefer using the carbide .45 acp because of the greator reduced sizing effort and using no lube.
*Sometimes you may need to use a small base die to reduce these cases to minimum SAAMI dimensions to fight brass spring back after sizing with some snug fitting bolt action chambers. After the first sizing with a small base die and the cases have been fired in "your" chamber a standard full length die can be used.
NOTE, pausing at the top of the ram stroke for 4-5 seconds reduces brass spring back and if using a standard die you "may" get away without using a small base die. A small base die reduces the case diameter approximately .003 more than a standard die and also pushes the case shoulder back approximately .003 more.(SAAMI minimum dimensions)
Military 7.62 cases are thicker in the base and have a thicker flash hole web that adds strength to the base of the case. The downside to these thicker cases is increased sizing effort when they are fired in larger diameter machine gun chambers.
Bottom line, after swaging or reaming the primer pocket, you end up with some very tough heavy duty .308 cases. (Ford Truck Tough)
