We do a lot of smallmouth fishing here with 4# line. If I can find it easily, I'll post a picture of a 4# line class world record I caught a few years ago. I didn't bother to send it in but it would have been 3# larger than the existing record. I believe it weighed 36# and change. I go lookee now. also have a great picture of one of the guides who worked for me but I doubt forum rules permit me showing it. She was a good guide, just dressed a tad skimpy.