The older is better softer and thicker , LC from 2005 on until recently is junk Hard and thin , the more soft and "plastic" a case is the longer it will last .
A friend of mine got hold of some DM44 and was floored at how consistent it is from case to case and sizes like butter, he is saving it for Match loading !!
Run it through a size die and you can feel the difference !!
But you are loading for a belt fed are you not ? So just stick to soft brass and you will get the most out of it, there is another key to brass life and that is neck annealing because brass work hardens if you anneal the necks it will not split some do it every reload (suggested for belt fed ) to every 3rd loading in tight chambers .
There is a tool used by match shooters that is not widely available invented by a Mass scale manufacturer reloader that checks for the dreaded separation bulge in the lower case just above the head and also allows you to see how much shoulder "bump" in a case , it looks like this
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It is rather simple the back two pins check for the Bulge the two in front are the datum point of the shoulder and your read out is the dial indicator .
For a Match shooter you would take a case fresh out of the chamber and zero the indicator ,then on resizing set the shoulder back "bump" it back .003" at most . Oh it also reads case head squareness
by rolling the case pressed into the gauge .
For a belt fed just as for a precision rifle the less you "work" the brass by dimensional change from firing the longer it will last in number of reloading`s !!
it will grow over firings so it needs to be trimmed for length . Annealing must only be on the neck and shoulder ,anneal the whole case and you have a Bomb !!
You can get most of this out of a tube case gauge type for less money But it takes time !! Hense he invented this gem 2-3 second and on tho the next ....:jedicrying: sadly we are loosing a Vet ,a manufacturer and most importantly a Friend to ill health ......He passed the rights on to another, an Armalite AR-50 gunsmith of considerable repute some one i know of but have never met .
Yea it is kinda spendy over $100 but i will not reload with out one !