[T. O'Heir]

"...and not one misfire..." That indicates something with the ammo isn't working right. The bullet weight doesn't matter, but factory or reload does.
"...ALWAYS on in the same charge hole..." That is what you need to check. Isn't likely, but still possible. Also not likely you started with the same cylinder every time either. Means you need try one shot out of each cylinder. A Sharpie dot on the back should do to mark each one as tried. Or leave the first case in so you know where you started. It's also doable with just a primer vs needing a range. Assumes you have a basement to play in.