I have been checking the extractor groove on a batch of Lapua brass as I marched it through several ladder tests with the tops of the ladders ( last 4 or 5 rounds ) being pretty stout .
After 4 firings I took the dial caliper to all the cases in this 50 lot and checked the primer pockets and ext. groove dimensions . 24 out of the 50 had expanded 5 thou in the groove and primer pockets are 2 thou under primer size . The other 26 are 2 to 3 thou larger in the groove than new and 3 to 4 thou smaller in the primer pockets than the primer .
I also checked the internal neck size after collet neck sizing with the Lee collet die . The necks are staying same as when first sized , that is , 4 thou under bullet size . This is true for all 50 cases .
Finally I sliced a case that was the most enlarged in the groove and primer pocket dimensions . Not having viewed cases before in this manner I would appreciate input on the pix I am hoping to attach to this post .
Bottom line is that I have been operating under a idea that when the groove dimensions are beyond 3 thou enlargement that the brass was likely to have case wall thinning to the point of separation . I don't know where or when I picked up this idea but I really don't want to throw away good brass .
Thanks as always guys , Jim B. [image]
Pic is pitimous cause my camera buff middle son isn't here to show me how to get the closeups in focus , this camera has more knobs sticking out of it than a sow that just had a litter . [image]