Four-eyed Buck: It was chilly, but not cold. I guestimate that it was around forty degrees. I'll check on the burr theory. As for the pistol ammo, I bought it at a gun show since I don't do any reloading myself. It was made by Alabama Ammo and am unsure of which primers they use. I haven't had much problem with their product and since this was my last box perhaps it was just a bad production run.
Yes Doc, the shotgun is out of the box. The primers have very shallow,off-center dimples. Not every shot out of the right tube failed, just some.