Technisub Ranger Variable Power Pneumatic Speargun

The variable power model of the Technisub Ranger is a bit of a mystery as to how it works, but I just found a better parts diagram and more importantly detailed photos of the gun's inner body that the outer rear handle slips over the top of. This construction is a variation on the earlier Jeans and Grinta guns, both of which had small diameter air tanks. Although appearances suggest otherwise the Ranger also has a smaller tank under an outer shroud that makes it look less like a grease gun and provides some angular lines.

Here are multiple photos of that inner body for the Ranger VP and it shows that rather than a control rod the guns used a rectangular metal slide to change the power settings. In the parts diagram we can see a spring loaded collar that slides on the inner barrel directly in front of this inner body and my guess is this moving collar is what the rectangular bar pushes open in one position and allows to close in the other. That would make this the transfer port piston plug equivalent that we see in Sten guns and all similar clones.

This is a different way to make a partitioned bulkhead gun, but needs circlips on the inner barrel to hold the power regulator items in place. The Grinta gun also used barrel circlips and these are easy to break when trying to remove and replace them on the inner barrel. Plus there is the danger of scratching the inner barrel's exterior which needs to be blemish free to make this system work in the Ranger. The Grinta used a throttle with a leak path always present, hence it had no easy load capability. On the Ranger you need a leak proof non-return valve and that is what the sliding forward collar is for easy or progressive loading. Thus the power control valve and one way valve are one and the same item. When muzzle loading increased pressure in the inner barrel pushes the collar forwards and when you stop pushing the collar slides back trapping the displaced air in the front part of the tank. That is how all partitioned bulkhead guns work, just how well it worked in the Ranger I don't know, having never used one.

You can see the power control metal slide location in this diagram.

I have annotated the drawing based on my experience of other guns.

I suspect at the top of the drawing they have mistakenly swapped the ring numbers for "O" rings 263.535 and 262.115.

You can think of the power regulator seen here as being of a similar action to the Salvimar power regulator, but instead of a curved segment seal mounted and pushed forwards by a long control rod, in the Ranger there is an annular seal sliding on the inner barrel tube mounted on a moving collar and being pushed forward by a metal slide moving inside the inner body. Whereas the Salvimar system has a spring on the control rod to push the segment seal backwards, for sealing in the Ranger it is a coil spring mounted around the inner barrel tube that pushes on the collar.

The upstream valve means that if the regulator valve is closed and the pressure in the inner barrel is for some reason lower than the tank in the front section of the gun the pressure imbalance will clamp the regulator valve closed resulting in it being almost impossible to move the power regulator. As with the Salvimar upstream valve guns the cure is to pump up the gun with the hand pump and rebalance the pressure throughout the gun which will then unclamp the regulator valve after which the power regulator lever will once more be easy to move. Forcing the lever could break something, so don't even try. The coil spring on the inner barrel will create a slight resistance when opening the power regulator valve, hence there are small indents in the handle molding to retain the lever in either position as the lower face of the lever must have a matching bump.

The power lever position retaining indents can be seen here.