As a thought, could the Pre-WWI fuze have been fired for training during WWI?
Also, rust is a chemical reaction; that means just putting oil will not stop it; but may inhibit it as it should create a reletivly oxygen free environment; albeit temporary. What did you use to stop the rust?
RC, initially I cleaned the dirt and rust off and used a crystalline wax on the pieces that I wanted to protect. After that it was kept in a temperature/humidity controlled room.
Three issues that I can think of that may cause the return of rust. 1) the wax was applied 20+ years ago. May need to reapply a coat. 2) protected items are stored with non-protected items which may speed up the breakdown of wax. 3) May need a better preservative.