[Dr. Strangelove]

Your is an interesting question. The three calibers you mention are perhaps the three least cost effective to reload, depending on how you look at cost. As Sevens pointed out, there is so much inexpensive ammo available for the 7.62x39 (.223 and .308 as well) that from a pure cost standpoint, it makes no sense to reload them. Just looking at ammo that goes boom and puts a hole in something downrange, I simply cannot load .223, .308, or 7.62 x 39 for less than I can purchase loaded cartridges.

Where you start to see a difference is when you begin to look at hunting or target type loads with more expensive bullets. A box of Hornady 154gr SST 7mm Rem Mag cartridges goes for about $32 -$50 for twenty depending on where you purchase them. I can load them for roughly 50 cents each, about a third to a quarter of the cost of factory ammo. I also load .223 and .308, I just don't try to compete with the surplus or cheap factory ammo, just like I don't try to make Budweiser when I brew beer.

Cost savings in reloading is a strange and wandering road, it is possible to realize significant savings in individual loads such as the 7mm example noted above, however I would say that overall I've never really saved any money. I just shoot more 7mm than I would if paying full price. If you enjoy tinkering and don't mind tedious details, by all means get into reloading. I enjoy the time spent at the bench, weighing every powder charge, loading 10 different loads with the same powder to maybe wring out that last bit of accuracy, etc. If put any kind of value on the time I spend at the loading bench, accounted for the price of my equipment (most which I've had for 20+ years so I don't care to factor that in anymore), or didn't have easy access to a place to shoot, I don't know that I would reload.

To sum up a long-winded answer, yes, you can save money by reloading, just not particularly on the three calibers you mentioned. As as others have mentioned, the more strange and rare the caliber, the higher the potential cost savings. I enjoy the control over the components and level of accuracy I attain by reloading, and I load all my hunting and target rounds, but I'm fine with letting the factory load the stuff I'm just going to play with, mainly because they can do it for less money.