Each gun is assembled in our facility in Virginia. During assembly, the latex bands are hand made on the day the gun is built (so they are as fresh as is possible). During the assembly, we also rig the shooting line. We sell our guns with a single wrap of line, but if you want a second wrap (a longer shooting line) we can easily make that change if the order is placed over the phone - and we do not charge extra for this.
Most people prefer a single wrap of shooting line, because the second wrap of line is more prone to tangling with the bottom etc. People that are shooting the largest guns in clear blue water (and when freediving in pelagic conditions) more commonly prefer a double wrap because it extends the shooting range which is very beneficial when the visibility is 50 or 150 feet, for example.
Larger, more powerful spearguns can hit with a lot of power at a distance of two wraps of line - so this extra line significantly extends the potential range of the gun. With very short guns there is a significant drop off in power as the distance extends past one wrap and into the two wrap distance.
Selecting the appropriate gun length for the conditions goes a long way to improving effectiveness. In general, shorter guns are easier to swing, faster to aim and easier to load. Longer guns offer increased range, more power and probably better accuracy at considerable distance than a shorter gun.
Also, in very limited visibility, a target pops up into range very quickly and may also move out of visibility very quickly as well and you may not get an opportunity to extend your arm fully. In these conditions, shots have to be made quickly. If you are hunting in 50 feet of visibility, you often have some time to stalk and approach and then aim ( the longer gun). So there are trade offs.
In general, you want the shortest gun that shoots to the limit of the visibility - obviously as visibility extends past 30 or 40 feet, this criterion is no longer attainable.
When diving in limited visibility, there is no benefit (and also some safety considerations) associated with using a gun that can hit something that is further away than you can see. Also, if you are shooting into holes or under ledges frequently, then a short gun is the tool for that application.
So when we discuss visibility, we are measuring how far away we can see something - as measured from our eyes (obviously). When discussing a speargun's range, there can be some ambiguity in how this is measured. I tend to think along the lines of: How far from my EYES can a shoot a fish?
If you apply this idea and understand that a speargun is normally shot with the arm extended with the elbow locked (or nearly so) and also that the speargun is launching the shaft from the far end (muzzle) of the speargun, then distance to target (or "range") is greater.
For example, if I hold my arm straight out, it is maybe 2 feet from my eye to my palm. If the gun is 2.5 feet long from the handle to the front end (muzzle), then the shaft is being launched from around 4.5 feet from my eye. So if the target is 8 feet from my eye, the distance the shaft has to actually move to impact the target is only about 3.5 feet (8 - 4.5).
When you asked about speargun range in the question above you asked the distance as measured from the tip (muzzle of the gun). There is absolutely no problem with framing the question in that manner, but this is where the opportunity for ambiguity may come into play.
Sorry for being so long winded.
Our shafts are made in South Africa and do not include rest tabs.
What visibility are you intending to hunt? If the visibility is around 15 feet, then a 80 or 90 cm gun would probably be the most common size selection.
Too bad we can't post videos as easily as photos (yet). You can use ScubaBoard posts as a draft for the descriptions and photo updates to your site.
