Glad to be able to help instead of feeling stupid all the time I am here
By the way: You pulled out your JOHNSON?!?! Glad I wasnt around...
My un-educated, spontaneious (that was NOT the correct spelling, was it?) guess, is that it was an early option, for an extra cost, too.
A reasonable theory might be that it was too expensive and demanded too much time to produce. As you all know, there are other examples of leather-covered scabbards that stopped being produced, and were replaced by others.