Another good perk...
This fall when deer season opend up here all the stores were waiting on delivery of SP 7.62x39, I seen a few boxes on a shelf at one store for $30 (mfs)... I had 100 at home in a MTM box that I had built over the summer... Instead of crying I was giggling all the way home about it... Many many advantages to hand rolling yer own.
That's the big one for me, too - not having to try to track down the right factory load when everyone's sold out.