Originally Posted by
DG
Duck, the answer is probably "no", since these things are not exactly precision instruments. I suspect the major manufacturers have some good manufacturing tolerances and QC, and that the majority of their lines are pretty close, but there is no real reason to make them EXACTLY the same. How precise does it need to be? If you need it to be a grain lighter, reel in three inches. And the first time you use it, and the second, and the first time it is cleaned, the weight is going to change a little bit anyway, with dirt or line cleaner or line surface wearing off.
And whether a 4wt line will work better on that rod is ENTIRELY a matter of your preference, your casting, your "feel" for the rod.