Perhaps I am naive, but I think 500 rounds of SD ammo is a little excessive even
Not really when you think about it.
Every time I shoot my carry revolver, the first rounds out the barrel are those I've been carrying.
If you shoot you carry pistol often (which everyone who carries should), then it wont take long at all go to go through 500 rounds.
You should be practicing with what you carry and fresh rounds should go in every time you shoot your last load.