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Is it all the same brand of brass? Primer pocket cleaned out?
Couple of thoughts. Maybe you've got the primer rod in upside down, or have the wrong one and you're not getting the primer pushed in flush. I've got that hand primer, and the rods can look alike, and can be inserted upside down.Also, when you say you've cleaned the primer pocket, was it from the pocket side, or with a tool you put into the mouth of the case? Do you have some tumbling media caught in the pocket? Sometimes the liquid polish you put into the tumbler will clump the media and cause it to stick inside the primer pocket.
Some of the 223 brass has crimped primer and even though the fired primer came out easy there is a sharp edge on the primer pocket that needs to be removed. I just use my deburring tool that I use on the inside of the case mouth. You just have to take the edge out not hog a big V in the pocket. Try it on a couple of cases and see if that helps. They make prime pocket reamers and swaging tool to take out the edge also.
Any chance at all you picked up a few of somebody else's cases? Some ammo makers put a "military" crimp on the primer. When you deprime they leave a burr. It won't be removed by a primer pocket cleaner. You can either buy a tool for it or give it a few turns with a countersinq bit. If you use a counrtersinq, Just remove the center bit that drills the pilot hole.
The upper two cases with the FC marking are definately NATO/Military cases and would have a crimp unless someone swaged the crimp out already. Check this Forum for more info: http://www.sksboards.com/smf/index.php?topic=34912.0They make a swaging tool for the primer pockets.