Sorry to hear about that, but it is understandable. Even very experienced shooters can have a "forgetful" moment. In fact, the more you shoot, the more chance there is for that to happen. I had an old Herter's .44 mag with a four inch barrel that was at the time by far the loudest firearm I'd ever shot. Didn't even have "hearing protection" back then in East Texas, I'm sure my hearing problems today got much of their start with that gun.
Mike