I have just acquired 2 1- lb. cans of Hodgdon's S4198. On the back they say, "Use regular 4198 Canister Data (This is Salvage 4198)"   B.E. Hodgdon, Inc., Merriam, Kansas.   

Apparently this is WWII powder. The cans have paper wrap-around labels that are pretty crude. The powder is still good and I intend to use it. I didn't realize any of this was still around. Comments?

4198 is one of the most consistent and forgiving powders there is.  Nice flat pressure curve, doesn't spike or detonate.   

I'd use it without hesitation.  Probably would load 10 cases, try it, and if it worked, mix it in with a half dozen other cans so I have a consistent lot instead of can to can variations.  That's what I do with the 4198 I use.  Over the past couple of years I have acquired a number of cans and partial cans from estates I buy.  I've mixed it in a large stainless steel bowl thoroughly, and then redistributed it into individual cans.   I use probably more 4198 than anything else.   

The above mixing advice is against the advice that manufacturers give and contradicts their warning to never mix powder lots.  However, as I've posted before, it makes sense and I can find absolutely no reason that it's dangerous, and it gives a better final product.  But, make your own decisions!