Until recently I assumed that a 5x leader and a 5x tippet from the same manufacturer had the same breaking strength, but this is apparently not the case. For example, The Orvis Mirage Fluorocarbon 5x tippet material has a claimed breaking strength of 5 pounds, while the Mirage Fluorocarbon knotless tapered leader has a claimed breaking strength of 3.2 pounds. (These numbers are taken from the packages.) Similarly, the claimed breaking strength of Orvis Nylon Super Strong tippet is 4.75 pounds, while the breaking strength of the 5x Nylon Super Strong knotless tapered leader is 3.2 pounds.

I contacted Orvis to confirm that these differences are real, and to find out why they occur. I was told that the differences were real and were caused by the extrusion process for making the leader. Somehow this manufacturing process causes the leader to be weaker than the corresponding tippet.

I have noted the same differences for other tippet/leader manufacturers (e.g., Seaguar), as well, so I think this is a difference that occurs for all manufacturers. I have not, however, looked carefully at the claimed breaking strengths for most of the other manufacturers.

The differences in breaking strength are surprisingly large. Taking as an example the Mirage 5x described above, the breaking strength of the leader is 36% lower than the tippet. This implies to me that a knotted leader is a stonger leader than a knotless leader of the same diameter, even allowing for the fact that the knots also cause a reduction in the stated breaking strength of about 15%.

In discussing this with the managers of a couple Orvis stores, they were unaware of this phenomenon, so I presume that most of us fishermen are also unaware of it. Based on this information, I don't think that I will be buying knotless tapered leaders anymore. Rather, I will be building my own leaders by knotting together tippet sections on a furled leader butt.