IME: Black powder and Pyrodex are equally corrosive, either is capable of ruining your gun unless promptly cleaned.
Poppycock!
I have been shooting real Black Powder in my guns since 1968.
Yes, I am lazy and seldom clean them right away. I try to clean them within a week. I am not going to admit here in public how long I have occasionally allowed my guns to sit without cleaning, suffice it to say it is far more than one week.
Bottom line: I have discovered over the years that not cleaning my guns immediately will not reduce them to a pile of rust.
I try to clean them within a week.
Also, I never use the word 'neutralize' when referring to cleaning Black Powder fouling. The key here is dilution, not neutralizing. Using plenty of water, fouling gets dissolved and washed away. Neutralizing, changing the pH to 7, does not even enter into the conversation.
Most of my BP shooting these days is with cartridges. Years ago, when corrosive primers were common, BP fouling coupled with corrosive primers made the fouling more corrosive. We do not use corrosive primers anymore, and BP fouling is no where near as corrosive as most shooters believe.
I do rinse out my brass within a few hours of shooting or it will turn green with verdigris if left unrinsed overnight. Again, dilution is the key, not neutralizing.
All this is my experience with real Black Powder.
I have no experience with Pyrodex, have only read about how nasty it is.