As a matter of interest Tomwolf, I was an Armourer ar the huge Ordnance Depot at Ngaruawahia during the 1967/68 when
NZ
was divesting itself of a load of No4's and I SAW with my own eyes the sealed crates of rifles that had been stored since they arrived during the war. I have written this all down on this forum if you want the full story, but in short, even if they were wrapped in grease, then NOTHING would/could have saved them from the ravages of the deck-cargo journey over, believe me. When some of the still sealed crates were opened by S/Sgts Danny Booker and Frank Sculley, they were just totally rust encrusted virtually unidentifiable heaps of pure iron oxide. No amount of grease or greased paper could have saved them. I recall that the inside of the 20-rifle crates were lined with a tar paper liner.
Canadian
Bren guns were the same although I only saw a couple of crates of those, say 30 guns. All written off on-site by WO2 Annandale and countersigned by Capt Reece the Ordnance Depot 2i/c as I seem to recall (or was it workshop boss Leo Francis?)
In my opinion, the only ones that survived were those taken out of crates, cleaned off and put into service. Don't believe me? Then another forum member who was there at the time, and another ex REME man, the late KimW saw the same with other kit being readied for disposal at the Ordnance Depot at Sylvia Park in Auckland.
I'd say let your eyes and gauges be the best judge OR being a bit brutal - but pragmatic - buy the rifle and not the fairy stories that are attached to them!
Anyone still see/in contact with Kim's family?