Oh yeah, you'll find that saltpeter, curing salt and sodium nitrates aren't all the same thing.
Saltpeter (potassium nitrate) isn't recommended for curing.
Curing salt is generally sodium nitrite (or nitrate, again, different animals with different purposes) mixed with common salt.
Sodium nitrate breaks down to sodium nitrite.
(listen to me, the 'expert' haha - just stuff I learned in the past couple of years...)
Again, learn the differences and how to use them properly.