I'm leaning towards it being a headspace thing. I had a Marlin 336 that did this with all the factory ammo I fed it, including LeverEvolution. Don't think the Hornady stuff would be loaded to low pressures. I wasn't too worried about it. I ended up selling the rifle before I got around to loading for it. Had I done so I'd just measure the fired cases in a headspace gauge and set up my FL die to bump the shoulder 2 thou so as not to overwork the brass.