Quote Originally Posted by oldster View Post
As near as I can remender, a "C" was about a 6 wt. ...
The only problem with this system was that there was no standard for what a letter meant. It was up to the manafacturer.
C was about a 7.

The problem wasn't that there was no standard; there was. The problem was that it referred to the diameter of the line, not it's weight. ("C" was .050 inches; "D" was .045, "E" was .040, etc) This worked fine when all lines were made of silk; one line of a given diameter weighed pretty much the same as any other line of the same diameter. When manufacturers started making line out of various plastic, with some lines designed to float and others to sink, diameter no longer meant much about how a line would work with a given rod. The modern standard is based on weight, rather than diameter, which gets you a lot closer, although it's not ideal either (read the thread about multi-weight rods.)