If it's very recent, it might be "Cowboy" ammo? Meaning plain lead in .44Mag cases, moving at under 1,000fps for CAS/SASS match legality? A lot of people buy .44Mag Vaqueros for CAS and then load such stuff for matches...CAS usually doesn't require "historic cartridges", only "historic power levels" .
Edited: just saw the word "old" - DOH! In .22s, "CB" means VERY low powered, sometimes primer only...is it possible these are some sort of "44 squib load"?