I trimmed all my cases to the correct length and then loaded for testing loads. 3 powders, 3 shots per load, and 6 groups not as high as the book maximum. 90 % of the cases including my lowest loads will have to be trimmed again. I have never see this before. It's my brothers gun which hasn't been preforming satisfactorily. No groups responded as I would expect so I quit with 15 of the 54 cartridges un-shoot. I was suspecting a action to wood stock issue so I took out the clip and will try again tomorrow. But the case stretch - could that be a head space problem?