See the General Information section FAQ area;
http://www.lugerforum.com/FAQ.html
Q: What is a "Black Widow" Luger?
A: Typically a 41 or a 42 dated chamber Mauser, toggle coded "byf" with black plastic grips (on about 20% of them). This was simply a marketing tactic employed, and the phase was coined by Ralph Shattuck (he tells me). It really worked. These guns have a black salt blued finish, black grips, and all blued (black color) small parts (trigger, safety lever and take down lever). Some of the 1940 vintage (a very few), and 41/42 Lugers had them also, but primiarly the "byf" with black grips are a "Black Widow". This was an American invention, and had no German basis at all! German collectors say "Huh?" sometimes, when you mention the term! Shown below is an example of a "Black Widow".
Thor
Ed