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223nut heres my post from a year or so ago
http://www.nzhuntingandshooting.co.nz/f10/my-poor-260-winchester-primers-do-again-21006/

223nut yep got a very large pit in the bolt face of my 260 from a primer failure and they fit super lose in the primer pockets also I just stay away ive still got 500 but I'm slowly working through...

if you know it likes 150 sst stick with them for reloading
choices for powder are endless but you cant go wrong with good old plane jane ar2208 its what most of the target shooters use or did when...