Nope, never heard of them in the breed, wish I did....
Have or have had bantams in wc black, wc blue, blue, khaki, wc khaki, all the laced, crele, cuckoo, black, white, black crested white, black tailed reds, and white laced reds, and tolbunt (large fowl). Just about all of them. but never a self blue!
Right now I am down to the bc whites, whites,a few wc black, mottled houdans, and crevecoeur in bantams, thanks to a massive predator invasion over the winter, cleaned up on some near blind polish in 2-3 nights, I was SICK to say the least