If you’ve just bought a CDR4 DEVILFISH, setting it up correctly is the key to getting the performance it was designed for.
In this guide, I walk through the full process of rigging and loading a double roller speargun — from installing the reel and routing the shooting line to tensioning the bands and loading the gun safely. Follow this setup and your CDR4 will remain clean, reliable, and ready for serious spearfishing.
Quick Guide: How to Rig and Load a Double Roller Speargun
To rig and load a double roller speargun like the CDR4 DEVILFISH, follow these steps:
Install the reel and run the reel line through the muzzle eye.
Insert the shaft and ensure the shooting line sits on top.
Attach the shooting line to the reel line using a Dyneema quick-release knot.
Route the shooting line through the muzzle guides and onto the line release.
Install the roller bands and align them along the barrel.
Pre-tension the bands in the correct sequence.
Load the rear band first onto the smaller fin, then the front band onto the larger fin.
Following the correct sequence ensures your roller speargun remains efficient, cleanly rigged, and reliable in the water.
What Comes with the CDR4 DEVILFISH
When you receive your CDR4 DEVILFISH, the core components are supplied ready to assemble.
You’ll have:
The CDR4 DEVILFISH speargun
A reel
A set of bands
A shaft
Shooting line already attached to the shaft
The setup process simply brings these components together into a clean, functional rig.
How to Install a Speargun Reel on the CDR4 DEVILFISH
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The reel installation is intentionally straightforward.
The reel slides directly onto the mounting rail on the gun and locks into place with a simple forward push. Once installed, release the tension on the reel line and run the line forward through the muzzle eye.
At this stage, you should have the reel mounted securely with the line running cleanly through the front of the gun.
This forms the foundation of the entire rigging system.
How to Insert the Speargun Shaft on the CDR4 DEVILFISH
Slide the shaft into the top handle mechanism and ensure the shooting line sits on top of the shaft. This positioning is important because it allows the line to run cleanly during the rigging process and prevents unnecessary tangling once the gun is loaded.
Once the shaft is seated properly, the next step is connecting the shooting line to the reel line.
How to Attach the Speargun Shooting Line on the CDR4 DEVILFISH
At the end of the shooting line you’ll find a Dyneema loop.
Rather than using clips, the CDR4 system uses a simple quick-release knot. This approach removes unnecessary hardware, eliminates rattle points, and creates a very strong connection that can still be undone quickly if needed.
To tie the knot:
Take the tag end of the line, leaving around 15–20cm of length.
Thread it through the Dyneema loop, and wrap it around three times.
Pull the loop through itself.
Tighten the knot firmly.
This knot is extremely reliable and can easily be tied or untied in the water. To release it, simply pull the tag end and the knot comes undone.
The simplicity of this system is intentional — strong, clean, and reliable.
How to Rig the Shooting Line on a Roller Speargun
Once the shooting line is connected to the reel line, it needs to be rigged correctly along the gun.
The line runs up through the inside of the muzzle and around the first triangle guide. From there it crosses over the top of the shaft before running underneath through the main groove between the rollers.
At this stage the line can pass on either side of the line guide. Both work equally well.
From there it runs down to the line release on the handle, back up and around the muzzle, repeated a few times.
Once the line is rigged correctly, tighten the reel slightly to remove any slack. Keeping the shooting line tight is important for maintaining a clean rig and preventing tangles.
How to Install the Bands on a Double Roller Speargun
With the shaft and line now rigged, the next step is installing the bands.
The bands simply slide into position through the CDR4 muzzle assembly. The design keeps the system compact and ensures the bands sit neatly in line with the barrel.
Once installed, the gun is ready to be pre-tensioned.
How to Pre-Tension the Bands on the CDR4 DEVILFISH
On the CDR4 DEVILFISH, the sequence is important.
Start with the top two rubbers, passing them through the middle of the lower bands. These connect to the first attachment points on the muzzle. It’s best to keep the attachment points facing upward so they remain easy to access.
When pulling the bands, it’s important to maintain some tension on both bands while attaching them. If only one is pulled, the other band can slip through the muzzle.
Once the first two bands are secured, the remaining bands attach to the top mounting points. After attaching them, flip the bands underneath so
How to De-Tension the CDR4 DEVILFISH After Use
At the end of each dive day, it’s good to relax the bands.
To do this, bring the bands up over the top of the barrel so they face upward. Here you reverse the sequence to pre-tensioning the speargun. Hold both bands firmly, release the first one, then release the second, and slowly let them go.
This removes the stored tension and extends the life of the rubber.
How to Load the CDR4 DEVILFISH
The CDR4 DEVILFISH features two roller fins on the shaft — one slightly taller than the other.
This difference determines the loading order.
The bands closest to you load first onto the smaller rear fin. Once this is secure, the top bands load onto the larger front fin.
At first glance it may look like the bands sit in the way of the second loading point, but they move aside easily, allowing the second band to load smoothly.
Once loaded, the bands should sit neatly parallel with the handles tucked away between them.
How to Safely Unload the Roller Gun
When unloading a roller speargun, never simply release the bands.
The stored energy can cause them to snap forward at a high velocity, potentially damaging the muzzle or other components.
Instead, lower the bands slowly and under control.
This method protects the gun and ensures the bands last longer.
Watch the Full Setup Video
If you’d like to see the full process step-by-step, you can watch the complete walkthrough here:
