For the most part, primers became non corrosive in the 1930s. They did use mercury and were hard on cases. The only exception I am aware of, military, and especially military match ammo was loaded with corrosive primers into the 1950s. '06 mainly. .30 carbine was never corrosive. So if the loader was a competitor who happened to have some corrosive large rifle primers... You just need to clean thoroughly and shouldn't have a problem. Cleaning is a good idea anyway. As said, shooting someone elses reloads is a risky business. A man I respected in almost all ways was quite proud, he would put a small amount of Red Dot into his 7x57 load before seating the bullet AND FOR a 93 Spanish Mauser from Sears! No, I don't want to shoot his reloads. And as said, pulling them down is not that hard... Luck. Happy trails.