Why are other consumers immediately jumping to the producers side?
You must not be reading the same thing as most everyone else. Obviously, the box and price tag on it are original and the ammo that originally came in it was factory. But, the ammo in it now (or at least some of it) likely is not. The OP does not remember actually buying the ammo 15+ years ago from the LGS. He assumes the ammo is factory because of the lgs's price tag on it. Mixed headstamps in the same box is a huge red flag that it's likely reloaded ammo.
The OP also stated "and then felt a nasty recoil on the 4th shot. then my hand went numb
Indicating that round was loaded way too hot.
As I stated in an earlier post, I bought what was claimed to be brand new factory ammo... my proof to the vendor that the "new" factory ammo he sold me was actually reloads was the brass was all headstamped MIDWAY. Midway never made ammo and Winchester never used Midway brass.