Jim;
Do you have any dates for the Pieper Demi-Block? This method is also often referred to as a dove-tailed Chopper Lump. It has often been stated this method began with BSA in England. From your info it would seem highly likely that Pieper preceded them with it. I had previously accepted that it was simply another name for the chopper lump, thanks for this additional info.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra