The right speargun length depends mainly on water visibility, the size of fish you target and where you hunt. As a rule of thumb, short guns of 50–80 cm suit murky water, holes and tight reef, mid-length guns of 85–110 cm are the best all-rounders, and long guns of 115–140 cm are built for clear bluewater and large pelagic fish. Rollerguns deliver more range for their length, so you can usually choose one a little shorter than an equivalent railgun.
Key takeaways
- Match gun length to typical visibility: you cannot hit what you cannot see, so extra length only helps when the water is clear enough to use it.
- Short guns (50–80 cm) are faster to swing and easier to handle in rocks, caves, kelp and poor visibility.
- Mid-length guns (85–110 cm) cover most European reef and coastal conditions.
- Long guns (115–140 cm) give the range and power for open water and big fish, but are slower to track and harder to load.
- A rollergun or a multi-band gun adds power without adding barrel length.
Why speargun length matters
Barrel length controls two things at once: how far the gun can shoot accurately and how easily you can move it underwater. A longer barrel allows longer bands and a longer shaft, which store more energy and keep the shaft stable over a greater distance. The trade-off is weight, inertia and drag. A long gun is slower to swing onto a fish that appears beside you, more awkward in a crevice and harder to load on the surface.
Choosing a length is therefore about finding the shortest gun that still reaches the fish you realistically get shots at. Buying a 130 cm gun for a coastline where visibility rarely passes five metres is one of the most common beginner mistakes.
Speargun length by conditions: quick reference
Use this table as a starting point. Ranges are typical guidance for band-powered railguns and conventional guns; local conditions and personal preference always come first.
| Gun length | Typical visibility | Hunting style | Typical targets |
|---|---|---|---|
| 50–75 cm | Under 4 m | Holes, caves, rocky shore, kelp, murky water | Smaller reef fish at close range |
| 75–95 cm | 4–8 m | General reef and shore diving, ambush in rocks | Reef and bottom fish of small to medium size |
| 95–115 cm | 8–15 m | Open reef, drop-offs, mixed hunting | Medium to larger reef fish, some coastal pelagics |
| 115–140 cm | 15 m and more | Bluewater, drifting, offshore pinnacles | Larger pelagic fish at longer range |
If you hunt in very different places, many spearfishers own two guns: a short reef gun and a longer open-water gun. If you can only have one, pick the length that fits the conditions you dive most often, not the ones you dream about.
Visibility: the deciding factor
A practical way to think about it is that most shots are taken at a distance well inside your visibility, because fish need to be clearly seen and identified first. In water where you see four metres, a gun that shoots accurately to six metres brings no real advantage, only extra bulk.
- Low visibility (under 4 m): choose a short, light gun that points quickly. Single-band aluminium guns are ideal here.
- Moderate visibility (4–10 m): a 75–100 cm gun gives a good balance of reach and handling.
- Clear water (over 10 m): longer guns start to pay off, especially when fish keep their distance.
Target fish and shot distance
Bigger, warier fish usually mean longer shots and a need for more power and penetration. Larger fish also call for a thicker shaft and more band power, which in turn needs a longer barrel to keep the shot accurate. Small reef species taken at close range in holes do not need that energy, and an over-powered long gun can be harder to aim precisely in a tight space.
Shaft diameter follows the same logic. Short guns are usually rigged with 6.3–7 mm shafts, while longer, more powerful guns carry 7.5 mm or 8 mm shafts. You can browse replacement shafts in our spears and shafts category.
Railgun vs rollergun: how type changes the length you need
A railgun or conventional band gun gets its power from bands stretched from the muzzle back to the shaft. A rollergun routes the bands around rollers at the muzzle and anchors them under the barrel, which gives a much longer power stroke from the same barrel length. In practice a rollergun shoots further than a railgun of equal length, so many divers choose one 10–20 cm shorter than the railgun they would otherwise use.
For example, the Rob Allen Tuna Roller Speargun has an aluminium rail barrel and a roller muzzle with four ceramic bearings, and Rob Allen states an effective range of approximately six times the barrel length from the muzzle tip. It is offered from 80 to 120 cm. Read our full comparison of railguns, rollerguns and conventional guns for more detail, or browse all Rob Allen rollerguns.
Reef vs bluewater spearfishing
Reef, rock and shore diving
Around reefs and rocks you move constantly, turn into holes and often meet fish at short range. Manoeuvrability matters more than maximum range. Guns from 50 to 100 cm are the usual choice. The Rob Allen Scorpia Speargun (50–80 cm, single 16 mm band, 6.3 mm tri-cut shaft) and the Rob Allen Cobia Speargun (50–90 cm, single 16 mm band, 6.6 mm shaft) are simple aluminium guns built for exactly this kind of diving.
Open water and bluewater
In clear open water fish often circle at the edge of visibility and shots are longer. Here a 110–140 cm railgun with multiple bands, or a rollergun, makes sense. The Rob Allen BlueFin Pro Speargun is a carbon triple-band railgun (3 x 14 mm bands, 7.5 mm shaft) available from 100 to 130 cm, and the Rob Allen GT Carbon Roller Speargun is a carbon rollergun offered from 90 to 140 cm.
Rob Allen spearguns by available length
The table below summarises lengths listed for spearguns currently in our speargun range.
| Model | Type | Barrel | Lengths |
|---|---|---|---|
| Scorpia | Conventional band gun | Aluminium | 50–80 cm |
| Cobia | Conventional band gun | Aluminium | 50–90 cm |
| Caranx Railgun | Railgun | Aluminium | 70–120 cm |
| Tuna Railgun | Railgun, double 16 mm bands | Aluminium | 60–140 cm |
| GT Carbon Railgun | Railgun, twin 16 mm bands | Carbon | 70–140 cm |
| BlueFin Pro | Railgun, triple band | Carbon | 100–130 cm |
| Havoc Timberline | Conventional, triple band | Carbon and mahogany | 100–130 cm |
| Tuna Roller | Rollergun | Aluminium | 80–120 cm |
| GT Carbon Roller | Rollergun | Carbon | 90–140 cm |
| Timberline Roller | Rollergun | Carbon hybrid and mahogany | 90–120 cm |
New models such as the Snapper Railgun, Sparid Railgun and Snapper Rollergun are listed as pre-order items in the speargun category.
Other factors to consider
- Your fitness and experience: long, powerful guns need more strength to load and more skill to aim. Start shorter and move up.
- Loading: multi-band and roller setups need more effort; a loading aid such as the Rob Allen Load Assist Speargun Loader can help with heavy bands.
- Travel: longer guns need longer bags. Check the bag length against your gun before you fly.
- Local rules: regulations on spearguns, seasons and protected species vary by country and region. Always check before you dive.
Summary: picking your length in three steps
- Estimate the visibility you usually dive in and pick the matching row in the table above.
- Adjust for your targets: go longer for bigger, warier fish; shorter for holes and tight reef.
- Decide on gun type: if you choose a rollergun, consider a slightly shorter length than the equivalent railgun.
FAQ
What is the best speargun length for a beginner?
For most beginners diving reefs and rocky coastlines, a gun of roughly 75–90 cm is a sensible first choice. It is easy to load, quick to aim and still reaches most fish you will see in average visibility.
Is a longer speargun more accurate?
A longer barrel keeps the shaft guided for longer and allows more power, which helps at range. At short range, however, a long gun is slower to swing and harder to aim in tight spots, so it is not automatically more accurate in practice.
How much shorter can a rollergun be than a railgun?
Because a rollergun has a longer power stroke, many divers choose one about 10–20 cm shorter than the railgun they would use in the same conditions. The exact difference depends on the bands and set-up.
Can I use one speargun for both reef and bluewater?
A mid-length gun of around 100–110 cm can cover both reasonably well, but it is a compromise. Divers who regularly do both often own a short reef gun and a long open-water gun.
What length speargun for the Mediterranean?
Conditions vary a lot by area and season. Many divers use 75–100 cm guns for rocky coastal hunting and longer guns in clear offshore water. Check local regulations, which differ between countries.