plenty of people do tumble loaded rounds, however, and i have never heard of rounds going off but it is not a safe thing to do!!!
firstly, there is the chance that a bullet meplat might strike a primer with enough force with dire consequences....
secondly, vibrating loaded rounds may affect the coating on the surface of the powder kernels, removing the coating by abbrasion and changing the characteristics of the powder from slow to fast burning.... many powders are the same base product but with different burn inhibitors coating the outsides of the kernels..... you could end up with too fast a burn and dramatic pressure increases....
i wouldn't do it!
