As the old timers tell us, COWWs are becoming less and less available as time goes by. Of the more common sources of lead, COWWs seem to be the most reliable sources of "enough" antimony and "some" tin. SOWWs are almost pure lead, range lead can be anything (but most likely average a bit of antimony and a bit of tin), and plumbers/sheet lead is almost pure. Radiation shielding seems to vary between very pure and some with a profile close to that of COWWs if I am reading things correctly.
I have a stash of COWW ingots that I will add to if such shows up at a price I find acceptable. In the meantime, it seems like SOWWs and range lead are the most readily available sources at modest prices (I do not smelt, so I am an ingot buyer). I shoot more 38 special than anything else, so I am thinking that I really should just save the COWWs for higher pressure applications and use the more readily available stuff. I have been successful at snooping around local thrift shops for inexpensive pewter, so I am thinking that some range lead plus 2 or 3% added pewter should produce sufficiently hard boolits for standard pressure 38 special. I pay little enough for the pewter that it doesn't add material cost to the total and the added tin should make the boolits fill out really nicely.
Any obvious problems with this way of thinking? Clearly if I wanted something more racy like Lyman #2 I could buy some rotometals superhard and mix up the desired alloy with SOWWs/range lead, superhard, and pewter, so a COWW dearth isn't the end of the world. Since I don't need to use it for 38s, I figure I might as well get used to using alternative sources.