Welll folks loaded up some 7mm mag and headed at to range (50) rds.. everything went great except for 3 rds that I touch the bullet and it moved. . Looks like neck tension were loose, but I full sized every single one of them.. its not super loose just enough to push down the bullet.. Question is were these safe to fire ???
I had that (the sliding bullets thing) happen once with win brass and 140 accubonds in my 7stw ammo. I killed an antelope at 300 yards with those rounds (only ammo I had with). Turns out the brass was a bit thin necked for my dad's redding stw dies. Got another set of dies and all is well. If I had collet dies I'd have simply stepped down a collet.
Zero neck tension will change the load a bit from what heavier neck tension will do for you, but the biggest problem lies in the fact that the pill can shift; if you get one at the lands and one set back from recoil the accuracy will go to pot. The one at the lands will likely also have higher pressure as it has no run to the lands.