Ok, so I managed to screw up my first ten cartridges and make them 0.07" inches too long (Hey, no one bats 1.000, right?

), so a headspace gauge is definitely in my future.
My question is, can I pull those cartridges apart with my bullet puller and re-use the already-primed brass and never-used bullets, and if so, what's the best way to clean them to get the last little bit of powder off of them?