Yep Ronin...the only thing to do is try. Maybe if the shavings were kept in a well-sealed container you might get away with being able to use them for a long time. And like you say, a shower of decent sparks may ignite some oxidised shavings anyway. Some environments may be much better than others too.
Trial and error is the best teacher.
Ever tried lighting a SMALL amount of rifle powder? You would have to have it sitting on some decent tinder because it would burn very quickly...but it is just a thought if you want to light a fire when you are out hunting. The head 'bends' off a .22 rimfire bullet fairly easily. This isn't something that I would want children to try.
Trial and error is the best teacher.
Ever tried lighting a SMALL amount of rifle powder? You would have to have it sitting on some decent tinder because it would burn very quickly...but it is just a thought if you want to light a fire when you are out hunting. The head 'bends' off a .22 rimfire bullet fairly easily. This isn't something that I would want children to try.