Here is a scanned copy of the the above article as published in the January 2013 Gear Guide issue of Fly fisherman magazine.
In the previous part 2 installment, TWO (2) hazards were discussed when trying to re-use the floating head line weight class for a sinking head. The Active-Line load appears to be a more telling story than the standardized effect of weight class. This part 3 installment is to explore what is behind Mystery door #3, an unpredictability we were left with from only having casted the unmodified final head in part 2. We will be chopping and assembling this unmodified head to get all 9 digits of the line matching zip code for that Zpey - or any other - rod. This is akin to getting both the right shoe length AND width size. At the end of this part 3, we will see behind door # 3 awaits some nice surprises, along with those that will make us ponder further depending on how far we want to go down the rabbit hole. Just as when we feel we are getting close to mastery, we are humbled when we simply end up as a better student.
In part 1, we introduced the maddening story of buying shoes in a fictitious deregulated shoe size industry. It doesn't take a large stretch of imagination to see that the setup for the shoe story is an appropriate analogy for AFS heads. Simply substitute your foot size with your Spey rod and your fitting shoe size with your matching Spey line (using the differing shoe colors for differing sink heads) and the connection is made.
My affinity for AFS heads largely comes from the ability to change the sink rate of the entire shooting head, giving me a much tunable sink rate to match differing depth presentation for various combination of fly and on-stream factors. So, my first step in properly loading the rod of choice, a Zpey 12'3" #8 EU class rod, was to find a proper loading AFS floating head. Although the rod lists a grain window of 338 to 416 grains, just like the process of finding the light colored shoe, I had to experiment with several heads; sometimes using heavier heads that came with truncated tips (perhaps in attempts to keep the weight within the rod's grain window) [footnote 1]. I eventually settled for a 400 grain AFS #7 floating head. This floating head discovery is akin to the light colored shoe process.
Let's indulge in a short discourse here. Imagine one day you went to a shoe store looking for a light colored pair of shoes. Knowing your size, you approach the sales person and inform her the size, the color, and brand you want. To your surprise, she politely informs you that the industry decided to deregulate the standards in shoe size, and that the only way to know the right fitting size is to actually try many sizes in the chosen color and brand. You find that news rather astounding, but you begrudgingly give in and instruct her to bring several sizes that came close in approximation. You try on a few sizes until you find size X that fit. The purchase is made and you move on with life.