Cartridges Cal .30 Blank M1909 "Not Vapor Proof"

I wanted to share this picture of a .30 M1909 Blank box with an odd “Not Vapor Proof” inscription.

Any idea if it refers to the cartridges themselves, or perhaps the packing in ammo cans which might have had deteriorated seals and not suitable for long term storage of combat ammunition?

John, I’m not sure, but since this is a recycled can I believe that it refers to the latter. Also, there is a later variation of this box marked both “Not Vapor Proof” and “Loaded with Recovered Chlorate Primed Cases” (WWII Denver headstamps).

Hi Fede,

interesting can.
I think the “not vapor proof” refers to the can and not to the cartridges.
I have quite a selection of blank boxes. Only those from Twin Cities (from which your can is) have
at some point in time the remark “chlorate primers” printed on hem (see picture below).
I have never seen a box with “not vapor proof” on it. On the other hand that doesn’t mean anything, of course


TW blanks_zpsisrvqs65.jpg~original

René, thanks for the extra information.