All of the C&H I have ever bought, was in steel cans.

The C&H I burned in the 70's and 80's is/was not as good as the GO or GOEX or even DuPont black powder. It is lower powered and needed considerably more of it to make the same speeds.
T7 or 777 is probably the best of the phony's even though it says (MSDS) that it contains perchlorates. According to Bill Knight, who actually analyzed it, it does not have that corrosive substance in it. He stated that if he could not obtain real BP, he would use T7. He figured that Hodgdon simply used the Pyrodex MSDS sheet when they developed it.
Black Mag 3 and Pyrodex do contain perchlorates however and their fouling is excessively hydroscopic and corrosive with just residual moisture. It actually has an affinity for iron molecules and seems to dissolves them.
As with ANY phony powder, good cleaning practices MUST be adhered to. some guys who use them, say they re-clean their guns for 3 days afterwards, re-cleaning them to make sure they get ALL that fouling out of the bore's pores.

Oh yes - wouldn't a cache of #6 be nice to have.