Hiya
Many of the RA guns have different names for different coutries. Here in South Africa, the green handled RA was simply called a Rob Allen railgun. In Australia, the same gun was called Tomahawk, Sniper, Sparid, etc, etc, all depending on the band and spear configuration.
There are basically TWO RA guns, the one with the older Simotal (picasso) grip (green) or the new Vecta Grip (Blue). The various names simply denote the band and spear configuration with-in the range.
The beauty of a RA railgun is that it performs GREAT straight out of the box. No modifications needed. How-ever, many spearo's like personalising their guns and have modified their guns.
Spear length's vary, dependant on individual spearo's preferences. They is generally, 30-40cm's overhang on the spears. My opinion is to simply use the gun as it comes from the manufacturer, as they know what works best for which set-up.
Popular band and spear combinations:
6.3mm or 6.6mm with a single 16mm band
7.0mm with a single 20mm band
7.0mm with 2x16mm bands
7.5mm with 2x16mm bands
Depending on what type of fish you hunt, the above will cover most spearing situations.
RA have released their new mini-shark fin tab spears for their guns!! Well worth looking at, if you're keen to pimp your gun!!
Regards
miles