Rigor will not pass in 30 minutes, it takes over 24, and sometimes longer if resting in the cold refrigerator. I can not answer how it wasn't tough as a child, but can say w/o a doubt if you are trying to eat any meat that is currently in rigor, might as well be eating chewing gum.
I was young...maybe there was more time between processing and eating. And maybe it was a morning to night thing and enough time had passed. I need to ask my mom and grandma to be certain. Regardless, I plan to brine mine the next go-round and see how that goes.
I concur on meat still in rigor. Even if you crockpot it, it will be chewy!