no pyrodex wont rust you barrel if you actually clean your rifle within a couple days. Its very consistent and very accurate. Most corrosive thing invested? Highly unlikely, i think that poster is just going a little to much over the edge. I've been shooting pyrodex since i was 14 years old and never had any rust problems whatsoever. Lazy cleaners are what causes the rust, even with T7, blackpowder, you name it.