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Old 09-13-2021, 03:11 AM   #1
popgun pete
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GIRS-TITAN Hydropneumatic Speargun

Here is another hydropneumatic speargun from Russia, but this one is made from titanium. Like the “Aquatech” models available some years ago this gun uses a releasing valve to shoot the spear out of the gun with a column of water that was injected when the gun was muzzle loaded, but this Girstitan gun controls the releasing valve with a mechanical release rather than a hydraulic locking chamber and pilot valve.

These guns were the subject of an article in the Russian “Athlete-Submariner” magazine many years ago and were back then produced in limited numbers. Now the gun has been revised to utilize modern molding methods whereby the rear handle is of all plastic construction and the metal body consisting of outer tank and inner barrel screws into it. The inner barrel is stainless steel and the rest of the gun is titanium and you can disassemble the gun by removing the front tank even though the front section remains pressurised. Production of these new guns started about a year ago and I only became aware of their existence when for a short period they were listed on Alibaba to gain some exposure, however it was only luck that I saw them as I was only there looking for a cheap sports watch.

A rather unique feature of this hydropneumatic gun is it is modular, you can have a short gun, a medium length gun and a longer gun by combining the two short and medium tank modules. A separate spear is available for each tank length.

These are the drawings and photographs of the gun’s various prototypes from the magazine.

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Old 09-13-2021, 03:16 AM   #2
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Re: GIRS-TITAN Hydropneumatic Speargun

This is the gun in its latest incarnation.



These photos show the gun fitted with the medium length tank with the small tank sitting alongside it.
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Old 09-13-2021, 03:18 AM   #3
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Re: GIRS-TITAN Hydropneumatic Speargun

An interesting aspect of this GIRS-TITAN gun is how you pump the gun to create the pressurised air in the tank. Like all the annular piston hydropneumatic guns the compressed air tank is in the nose end of the gun which means a rear pumping attachment will not work. Usually the hand pump straps onto the nose of the gun with a tank clamping arrangement and stands perpendicular to the gun's longitudinal axis. However this gun is rather different as you unscrew the muzzle and replace it with a plug which uses the same muzzle attachment thread and then insert a spear tail first into the rear of the gun’s inner barrel after unscrewing the rear handle and pulling out the releasing valve. The spear is pushed into the inner barrel a short distance and then trapped in the gun by using a bush fitting which replaces the rear handle and converts the entire gun body into a pump. The tubular hand loader now becomes the pump handle by screwing it onto the threaded end of the spear which normally carries the spear tip but is now facing rearwards. The spear is now a pump rod (it has a tail seal which now serves as the pump piston). You pressurise the gun in the usual way with multiple pump strokes after which those extra parts are removed from the gun and the muzzle, releasing valve and rear pistol grip handle are reinstated ready for spearfishing. To let pressurised air out there is an air release screw (part 17) under the muzzle end of the gun that radially penetrates the front pressure bulkhead. This bulkhead is set back from the muzzle and the outer nose cone that can function as a line spool.
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Old 09-13-2021, 03:24 AM   #4
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Re: GIRS-TITAN Hydropneumatic Speargun

Some diagrams from the gun's handbook.


The "Combi" set which contains all the parts for three guns.
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Old 09-13-2021, 04:38 PM   #5
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Re: GIRS-TITAN Hydropneumatic Speargun

This is how the gun shoots as compressed air drives the annular piston rearwards as a result of the releasing valve uncorking the rear of the inner barrel thus allowing water under pressure to escape down it. Because water is incompressible the water has to speed up as it moves into the smaller diameter inner barrel which means it travels much faster than the annular piston does and therefore can propel the spear at high velocity.

Pulling the trigger simultaneously frees the line release lever and the releasing valve, the line wraps are wound back and forth on top of the gun which is an arrangement commonly seen on guns in that part of the world. The Soviet-era RPS-3 hydropneumatic gun pioneered this layout but had the undesirable trait of losing synchronisation between the shot and freeing the rear line release lever which could result in the spear flying and the shooting line snapping without releasing any wraps. The string that passed for shooting line in those days could not take the rapid jerk and the 9 mm diameter spear then disappeared into a weedy bottom never to be found again.
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Old 09-13-2021, 04:44 PM   #6
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Re: GIRS-TITAN Hydropneumatic Speargun

The grip handle and releasing valve before fitting it in the handle.

Close-up of the releasing valve.

The releasing valve in the discharged position which is indicated by the line release finger being tipped forwards.
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Old 09-13-2021, 07:04 PM   #7
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Re: GIRS-TITAN Hydropneumatic Speargun

This diagram shows how water injected during muzzle loading squeezes past the rubber cuff on the releasing valve by pushing it back on its biasing spring while the releasing valve body remains locked in place by the trigger mechanism.
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