Cabela's, Amazon, or any good reloading store.
I cleaned 7.62's in a large tumbler. I tried a few batches with the steel pins, but the pain of extracting all of pins compared to how clean the cases came out without using pins made me put the pins away and I haven't used them since. Others may feel strongly about using pins, but a good amount of cleaner and a few hours in the tumbler is good enough for me.
I've attached a photo of a load of 7.62 that I cleaned without pins using distilled water. I think I used the RCBS brass cleaner in this batch. I run the brass for two full cycles, rinse with tap water, then dry them for several hours in the Franklin Armory brass dryer. I've cleaned thousands of rounds this way without any issues.