Comparing very old Pyrodex against new Pyrodex for possible powder degradation is problematic because they are not the same powder. Pyrodex has undergone several modifications since the original patent in the 1970s. New Pyrodex is more powerful that the earlier powder.


This is the patent formulation:


45 parts of potassium nitrate
9 parts of charcoal
6 parts of sulfur
19 parts of potassium perchlorate
11 parts of sodium benzoate
6 parts of dicyanamide
1 to 4 parts of water



The current SDS for Pyrodex lists:

30 parts of potassium nitrate
8 parts of charcoal
8 parts of sulfur
30 parts of potassium perchlorate


http://www.pyrodex.com/msds.html