Charley is right!

It is NOT the mercury in some primers that makes them corrosive, it is the potassium chlorate! In addition, it is ONLY the primer deposits in corrosive smokeless powder ammo that has ever been corrosive. Initially, the old boys thought it was the powder fouiling, hence such concotions as "Hoppe's No. 9 Nitro Powder Solvent". But it never was the powder fouling causing the problem-just the primer salts.

Mercuric primers are essentially noncorrosive, BUT the mercuryruins the brass of the case by causing the brass to lose resilience and fracture, thus rendering the cases unfit for reloading after the shot. Mercuric priming was pretty much abandoned by all countries except Switzerland early in the 20th Century-and the Germans had figured it out and developed non-corrosive priming[RWS Sinoxid] a number of years before we in the U.S. had even figured out what was really ruining our barrels! I guess we couldn't read German technical publications-not printed in English!!

The U.S. Army had changed over completely to the use of non-corrosive priming in .30 cal. M2 ball ammo by about 1956-the various arsenals changed over at different times, beginning in about 1952.

U.S. 7.62X51mm NATO ammo has always used noncorrosive primers, as has ALL U.S. .30Carbine ammo. BUT, it is diffficult enough to know exactly whether U.S. made M2 ball ammo fromthe 1950's is noncorrosive or not, and I doubt that toomany people can give you a definitive statement regarding ANY military ammo made in other countries.

To be safe, I'd treat that stuff as if it were corrosive, and clean your rifle with hot, soapy water after shooting that ammo. I am not aware of ANY solvent, other than water, that is guaranteed to remove corrosive primer salts. Old G.I. bore cleaner was formulated to do so, but we used to clean our M1's with hot water anyway, just to be sure, because there were reports of bores rusting AFTER they had allegedly been cleaned with G.I. solvent alone. Maybe troops didn't do a good job, who knows??