If anyone is interested.

Goosic, I was reading the section in the Sierra Ed. V reloading manual on gas gun reloading and came across this description of reloading M852 match cases.  I don’t know it it apples to the lot you have, but you might want to look for a rolled-in cannelure just in front of the extractor groove.  

Looks like they may have had the black tar bullet sealant.  That stuff would practically weld the bullet to the case after 20 or more years of storage.  Shooters would break the seal before firing these cartridges by using a bullet seating die to push the bullet into the case just far enough to break the sealant.  It’s surprising how much force it takes to break this seal. 

 Yes, the black residue inside the case mouth.  Is that Tempilstick? 

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The problem explained in the Sierra Manual refers to reloading these cases, not the original problem they had with head separations occurring on firing of the factory loaded ammunition.  The issue with reloading the cases continued until the knurling was discontinued, although apparently not predictable.