thank you for the pics, could be your magazin stands in another angle that brings the tip of the bullet closer to the barrel. I have 1 mm too much between the feed lips and the barrel with common 7,62x39 oal. when cycle the action in slow motion the cartridge will jump out of its way because the magazine will kick the butt when the cartridge leave the feed lips and the next round come up.
it did not happen when you move the bolt in common speed because of the inertia of all parts involved.