Loose powder eliminates that gap you're worried about. Just tamp the load down the same every time. Eventually you will seat a bullet without any powder. If someone claims they haven't they are either a liar or have not shot enough. That's where its nice to have a removable breech plug. Pull the plug, push out the the bullet, throw it away and start again. Your breech plug not seating the primer all the way in bothers me but if you are an engineer, you can measure the depth of the hole.