In this series I will try as fully as I'm able, to cover everything I know about fishing and casting the shootinghead. And since this is Sexyloops, we'll even cover cutting flylines to pieces and gaining something from it.
I would like to begin by defining a shootinghead. It has nothing to do with firearms, but it does have something to do with gunning for maximum distance. A shootinghead is really only half of the story, as this is really something of a “line-system”. The shootinghead is the belly of the system, in many ways equivalent to the belly of a WF line. Behind the shootinghead is of course the running – or shootingline (I'll from here on refer to it as runningline. Some people discern between runningline and shootingline, a shootingline being a monofilament and a runningline being a coated line, but this is most confusing and therefore I'll refrain from this separation of terms).
The runningline is always of course a level line and as indicated above, you have some choices. The most commonly is probably a thin, level, floating and coated flyline with a braided core as most normal flylines. Coated runninglines also come in a version with a monofilament core.
This has both advantages and disadvantages. The advantage is that the monofilament core is thinner than its braided cousin for a given breaking strain, thus allowing for more coating leading to better durability, given the same outer diameter of the two. Or the other way around, given the same amount of coating on a core of given breaking strain, the monofilament cored line will be thinner than the braided core one! The major disadvantage is that one is unable to make a blind-splice loop to connect runningline to the shootinghead. Both types come in several thicknesses appropriate to different uses (generally, the heavier the equipment, the thicker runningline used, but I'll elaborate on these details later).
Pure monofilament runninglines are also available in different makes. As I see it, two types dominate the market. The Flat Beam type and standard spinning line. The FlatBeam types are monofilament, which is oval in cross-section. This should lead to fewer tangles (which it does in my experience). Flat Beam is only one brand, there are many others, but it makes no sense in going over them, since the only difference is colour and thickness. Standard spinning line is also popular in some parts of the world, especially the yellow Stren in 0,40mm, which is very popular here in Denmark. Both types are used in various thicknesses. They have the disadvantage that they have to be treated with floatant in order to, you guessed it, float :-).
Then there is the braided runningline. These types cast very well, but seem to be quite hard of the guides of the rod. They are usually available in two or three thicknesses. They float quite well and given a treatment of floatant, the stay afloat for a long time, because the floatant gets trapped in the braid. Finally we have the hollow, monofilament runningline. This type is not very common, but I think they'll get more popular. Because they are hollow, they float quite well. And they seem like a good compromise between the maximum distance one achieves with mono and the more pretty cast achieved with coated line.
The chosen connection between shootinghead and runningline is dependent on the choice of runningline and sometimes also shootinghead. If both have braided cores, the blind-splice loop on both parts make it easy to change shootingheads and the connection is slim, simple to use and easy to make. It allows swift changes of heads to accommodate changing conditions such as rising water, constricted space and so on. The braided runninglines are very easy to blind splice and the splice is very elegant. Both monofilament types are usually best connected to the head using a needle or nail knot. It's difficult to make loops on monofilament lines, but I have a few tricks which I'll disclose later when going into detail on the different kinds of connections).
The different runninglines are also very different to cast, which I'll go over later.
Of course shootingheads come in an even more dizzying array of densities, lengths, tapers and coatings. Needless to say that you should use sinking ones when you need to get the fly down deep, floating ones when you fish shallow water and for the pleasure of casting it and use the intermediate when you can't make a decision (Paul would say we should get rid of them all, only carry a floater and not be attached to our shootingheads at all – which on the other hand would make it quite difficult to retrieve them :-))!!!
(I have never said any such thing :-)) and the following is Viking Lars' disclaimer! – Paul)
Since my experience is mainly with floating ones, the following might not necessarily apply to sinking lines. I only ever use sinking shootingheads in the small rivers in which I fish for seatrout (and I only use them because I haven't yet been able to afford a Rio Versitip :-). And I have only very limited experience with using shootingheads on doublehanders, so the following might only be valid for singlehanders (in fact I have very little experience in doublehanders in general).
Lars Chr. Bentson