I have only neck turned cases I have down sized, like 223 to 221 Fire Ball, because I have to to get them to fit. I am fussy about accuracy, but I have not gone to that extreme yet, but never say never. I have only crimped the straight walled cases. I have not crimped bottle necked cartridges. I try to seat the bullets into the lands, so I feel a crimp is not needed. But, I have been thinking about crimping some of them lately that do not reach the lands for one reason or another, never say never. I have hesitated, because it works the neck more, shortening the case life. I have not shot cast bullets in bottle necked cases, but I would think that would be a necessity because the cast bullets do not have much resistance in the barrel. Never say never.