I've shot Pyrodex that I know is at least 5 yrs old..lmao..
I bought that big ole bottle one heck of a long time ago..just fer kicks, put it in the loader this year..first hit..**boom!**
I always kept the lid tight, and it sat in my gunrack ferever.
I had over 1/2 bottle left, dern sure wont gonna waste it!
