There are two different types of shooting lines. In no particular order. they are:
Monofilament (usually nylon - perhaps always - not sure if anyone ever mono shooting lines of any other material).
Coated - built like a flyline on a core, coated with either PVC or PE. They’re usually level and come in different thicknesses.
In the 90ies braided shooting lines were popular, and to be honest, they cast and fished exceptionally well. They were noisy, but absolutely no stretch and the sawed through the rings on your rod in a year or two, and I suspect that’s why (I think) nobody makes or uses them anymore.
The big advantage of monofilament nylon shooting lines (henceforth mono) is low weight and low friction. Both are great benefits in casting for distance. Not necessarily ultimate distance, but for repetitive distance casting, which is 95% of what we do along the Scandinavian coastlines, a shooting head with mono shooting line just reaches 25+ meters easier and faster then WF-lines, and more importantly, offer what for me is a very important feature - easy density changes.
Mono comes in many different types.
1. Different diameters.
2. Round or flat.
I usually choose slightly thicker mono than standard recommendations, and all producers have slightly different diameters. As an example, the new Scientific Anglers Absolute Shooting Line (flat mono) comes in 25, 35, 42 and 50lbs breaking strain. Thicknesses are 25lbs/017” (0,43mm); 35lbs/019” (0,48mm; 42lbs/0.22” (0,56mm); 50lbs/0.52” (0,64mm). Across different manufacturers breaking strains and diameters will change of course, but the intervals are fairly uniform, and vary only a little.
Flat mono has a tendency to tangle less, which is a great benefit and it also takes up less space on the reel, often allowing you to go down a reel size and still have a decent amount of backing. It casts further than coated lines because of less friction and lower weight, but this also means it doesn’t perform as well against the wind, where I find a coated line is a little better. In strong sidewind, you’ll also have to compensate with a deep reach into the wind to counteract the deep bow the wind will put into your shooting line as soon as you let it go - especially when using mono.
Flat mono ties very - well, flat knots that slide easily through the rings.
Round mono may have a slightly higher “tangle-rate”, but tangles are easier to undo, and the line doesn’t kink as much when it does tangle. For me, the main benefit in round mono lies in durability - it’s more durable than flat mono, but does tangle more. Knots are bulkier, but overall I think it casts much the same.
When using mono it’s imperative that you make sure your rings are in perfect order. The slightest imperfection will quickly wear through any mono. Generally mono has a limited lifetime, and should simply be considered a “consumable” that needs to be changes now and then. Don’t expect any mono to last 50+ fishing trips. I’d be content with 20.
Carrying on with that theme, coated shooting lines are more durable, especially if you take good care of them, keep them clean and lubricate every now and then. Minute nicks in the rings will damage coated lines too, but they’re more resilient.
I think the thinnest coated flyline on the market is the Vision Ultra Light Nymph, which is really a euro nymphing line, but several friends use it as a shooting line, and say it works great with good durability, and really more or less combines the best of both coated and mono. This coated, level line is only 0,58mm thick, which is impressive. I’ve cast it, and it really does perform very well, but I haven’t fished it.
Most companies make coated shooting lines and in several thicknesses, and I even think more are making them on non-stretch cores, which improves bite-detection greatly.
On coated shooting lines you can splice low-friction loops, which I think is very nice. They are also easier to handle than mono, when not using a line tray.
On that subject, I’ve begun using a line tray (well, a Flexi Stripper), even when fishing for sea trout and salmon with my single handler. Not because I cast much further, but it does make it very easy to keep the shooting line free from tangling in the dry grass. That’s not the main reason either, though. No, when I fish single handers and double haul with 2-3-4 loops og shooting line in my left hand, I very often tangle on the fighting butt, and that really drives me crazy.
Coated shooting lines do impair the sinking rate on sinking shooting heads a little ( but noticeably), so if getting the absolute most out of your sinking shooting heads, mono is the way to go.
Coated shooting lines delivers are nicer cast and a better turnover, so if you’re casting big flies on light(fish) equipment, coated is the best choice. All my pike outfits are on coated shooting lines, for instance.
OK - I re-wrote this to organise it a little better. I’m not sure I accomplished that, but I hope you can make some sense of it. I am listening to the new Tool-album writing this, and my attention drifts.
Let me finish one note, and set something straight:
The thin line attached to the head of a WF-line is called a running line - no matter how and where it’s made. The thin line attached to a shooting head is a shooting line. Don’t kill the messenger - it’s just the way it is (says Bruce).
And at some point, you at least need to try using either a FlexiStripper or a “real” line tray. I use both - FlexiStripper mostly in the rivers and in my float tube/pontoon boat and my preferred Baskette line tray when wading any still water.
Have a great weekend! Lars