The right band length depends on four things: the speargun model, the barrel length, the band diameter and the type of rubber. Rob Allen publishes an official rubber chart for its guns, and the tables below follow the Rob Allen Rubber Chart 2023. Find your gun, read across from its barrel length and you have the band length to cut or order.
Key takeaways
- Each Rob Allen model has its own band lengths. A 100 cm Tuna and a 100 cm Caranx do not use the same band.
- Blue rubber and black/green rubber have different lengths. Use the column for the rubber you have.
- A shorter band is more powerful but harder to load. A longer band is easier to load but has less power.
- Rollerguns use shorter bands than conventional guns of the same barrel length.
- In cold water, choose a band a few centimetres longer than standard.
Why band length matters
A speargun band stores energy when you stretch it onto the shaft. A band that is too short is very hard to load and puts extra strain on the rubber, the wishbone and the shaft notches. A band that is too long does not stretch enough, so the shaft leaves the gun slowly and loses range. The lengths in the Rob Allen chart are a balance between power and loading effort for each gun.
How to read the chart
- Barrel is the length of the gun barrel, the number in the model name: a Tuna 90 has a 90 cm barrel.
- Blue / black-green: the first number is for Rob Allen blue rubber, the second for black or green rubber.
- The band diameter is in the table heading: 14 mm, 16 mm, 18 mm or 20 mm.
- The chart lists the length of the rubber itself. Measure an old band the same way: the rubber only, relaxed, without the wishbone.
Conventional guns: Snapper, Mahi, Sparid, Tuna, Scorpia, Cobia
Lengths for 14 mm and 16 mm bands, shown as blue / black-green. Scorpia and Cobia are listed with black rubber only. Models in our shop: Rob Allen Tuna Railgun, Rob Allen Cobia, Rob Allen Scorpia.
| Barrel | Snapper / Mahi 14 mm | Sparid 16 mm | Tuna 16 mm | Scorpia / Cobia 16 mm (black) |
|---|---|---|---|---|
| 50 cm | 40 / 45 cm | 40 / 45 cm | 43 / 45 cm | 40 cm |
| 60 cm | 43 / 48 cm | 43 / 48 cm | 45 / 48 cm | 43 cm |
| 70 cm | 45 / 50 cm | 45 / 50 cm | 48 / 50 cm | 45 cm |
| 80 cm | 48 / 55 cm | 48 / 55 cm | 50 / 55 cm | 48 cm |
| 90 cm | 50 / 60 cm | 50 / 60 cm | 55 / 60 cm | 50 cm |
| 100 cm | 55 / 65 cm | 55 / 65 cm | 60 / 65 cm | 55 cm |
| 110 cm | 60 / 70 cm | 60 / 70 cm | 65 / 70 cm | 60 cm |
| 120 cm | 65 / 80 cm | 65 / 80 cm | 70 / 80 cm | 65 cm |
| 130 cm | 70 / 85 cm | 70 / 85 cm | 80 / 85 cm | 70 cm |
| 140 cm | 80 / 90 cm | 80 / 90 cm | 85 / 90 cm | 80 cm |
| 150 cm | 85 / 95 cm | – | 90 / 95 cm | – |
| 160 cm | – | – | 95 / 100 cm | – |
| 170 cm | – | – | 105 / 110 cm | – |
Conventional guns with thicker bands: Custom 18 mm and Caranx 20 mm
Shown as blue / black-green. See the Rob Allen Caranx Railgun 1200.
| Barrel | Custom 18 mm | Caranx 20 mm |
|---|---|---|
| 50 cm | 50 / 55 cm | – |
| 60 cm | 55 / 60 cm | – |
| 70 cm | 60 / 65 cm | 60 / 65 cm |
| 80 cm | 65 / 70 cm | 65 / 70 cm |
| 90 cm | 70 / 75 cm | 70 / 75 cm |
| 100 cm | 75 / 80 cm | 75 / 80 cm |
| 110 cm | 80 / 85 cm | 80 / 85 cm |
| 120 cm | 85 / 90 cm | 85 / 90 cm |
| 130 cm | 90 / 100 cm | 90 / 100 cm |
| 140 cm | 100 / 110 cm | 100 / 110 cm |
Rollerguns: Tuna/GT Roller, Timberline GT Roller, Snapper/Mahi Roller
A rollergun band runs around the muzzle rollers and back, so it is shorter than a band for a conventional gun of the same barrel length. Shown as blue / black-green. Models in our shop: Rob Allen Tuna Roller, Rob Allen GT Carbon Roller, Rob Allen Timberline Roller.
| Barrel | Tuna / GT Roller 16 mm | Timberline GT Roller 16 mm | Snapper / Mahi Roller 14 mm |
|---|---|---|---|
| 50 cm | – | 35 / 40 cm | 30 / 35 cm |
| 60 cm | 40 / 45 cm | 40 / 45 cm | 35 / 40 cm |
| 70 cm | 45 / 50 cm | 45 / 50 cm | 40 / 45 cm |
| 80 cm | 50 / 55 cm | 50 / 55 cm | 45 / 50 cm |
| 90 cm | 55 / 60 cm | 55 / 60 cm | 50 / 55 cm |
| 100 cm | 60 / 65 cm | 60 / 65 cm | 55 / 60 cm |
| 110 cm | 65 / 70 cm | 65 / 70 cm | 60 / 65 cm |
| 120 cm | 70 / 75 cm | 70 / 75 cm | 65 / 70 cm |
| 130 cm | 80 / 80 cm | 75 / 80 cm | 70 / 75 cm |
Source: Rob Allen Rubber Chart 2023. For models not listed, copy the length of the original band or ask us.
Bands for cold water
Rubber gets stiffer as the water gets colder. In cold seas, such as Norway or Alaska, the standard band supplied with the gun can become very hard to load, especially in thick gloves and a thick wetsuit. Many spearfishers there choose bands a few centimetres longer than standard, often one step up the chart. Loading is easier and safer, and you lose only a little power.
Making your own bands
You can rig bands from bulk rubber: cut the rubber to the length from the chart, fit a wishbone and tie it off. You will need:
- Rob Allen Tuna Blue Bulk Rubber, sold per 10 cm in 14, 16 and 20 mm
- A wishbone, for example the Dyneema Wishbone, Cable Wishbone or Easy Load Wishbone
- The Rob Allen Wishbone Tool to fit the wishbone into the rubber
Inspect bands before every trip and replace them at the first sign of cracks or cuts. See our speargun maintenance guide for more.
FAQ
How long should my speargun band be?
It depends on the gun model, barrel length, band diameter and rubber type. Find your model and barrel length in the Rob Allen chart above and use the column for your rubber: blue or black/green.
Why are blue bands shorter than black or green bands?
Rob Allen lists separate lengths because the rubbers stretch differently. Always use the length from the column that matches the rubber you are rigging.
Should I use longer bands in cold water?
Often, yes. Cold rubber is stiffer and harder to stretch, so in places like Norway or Alaska many spearfishers fit bands a few centimetres longer than the standard band supplied with the gun. Loading gets easier, at the cost of a little power.
How do I measure a speargun band?
The chart lists the length of the rubber itself. Measure your old band the same way: the rubber only, relaxed, without the wishbone.
My gun is not in the chart. What should I do?
Measure the original band that came with the gun and copy it, or email us at info@gospear.eu with the model and barrel length and we will help you choose.