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Hydro/pneumatic gun

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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Adjustment diagram showing how the small bolts in the trigger slide can provide a small delay in the trigger pull discharging the RPS-3, in which time the line release blocking cam can be moved to free the sprung loaded line release finger. When the spear leaves the gun the shooting line can then overcome the wire torsion biasing spring on this lever and tip the line release finger forwards which will cause it to disappear into the frame of the gun's rear body. If it is not free to move then the shooting line will probably break and the spear will be lost as the 9 mm diameter spear has considerable momentum. After the shot the line release finger returns to its usual position sticking up at the rear of the gun, as these Soviet-era guns carry their line wraps along the top of the gun body.
RPS-3 adjustment.jpg
 
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This thread has pretty well ransacked every nuance of the RPS-3 hydropneumatic gun, but I was recently looking at the Russian patent for the gun wondering what the second page is all about as it is illegible with a terrible quality scan of the text.

Looking at the patent diagram and pumping up its size while knowing what the final product looked like it is now apparent what that second page said.
RPS-3 Original patent drawing.jpg

Originally the idea was for the trigger to pull the trigger rod shown in blue out from under the tail of the sear or release lever shown in red. The angled mushroom head on the spear tail is trying to push the sear lever aside, but it cannot budge while the trigger rod’s front pin is stuck under its rear end. Once that sliding pin is withdrawn by pulling the trigger then the spear can fly from the gun. In figure 2, which is a slight enlargement of the trigger operating system, it is showing if you pull the trigger back distance "a" the gun shoots, but if you reverse the direction and push the rod forwards distance "b" then tiny radial holes in the rod send water back from the hydrostatic pressure area via a hollow in the sliding trigger rod body and pin. Note that using that depressurising system to vary the power of the shot and you will eventually nibble the seal on the slim rod out. This was probably easier to draw than to make so they created the compact laterally displaced sear disc instead which has been covered previously on this thread Then just to add to complexity they added the safety system with the rocking bar which is actuated by pushing a curved element forwards that looks like a second trigger in the final gun.

Figure 3 shows a section through the rubber ring inlet valve that allows air to be pumped into the gun. The air release screw was added later and is not shown. An awl can be used to depress the rubber ring valve, but you risk putting a hole in it.

What is interesting is that this original sear lever is very much like the one used in the Omer Airbalete, One Air and Omer XII guns, except you push a pin forwards to fire those guns near the gun's periphery rather than withdraw a pin on the centreline. This is because Omer needed to attach the air hand pump from the rear end, something that you cannot do with a trigger mechanism in the way on the gun’s centreline.
 
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USSR patent! Not Russia! These are different countries!
Well they are now, but isn’t this a Soviet Patent, you can see it on the previous page. Actually many of the Soviet era spearguns were made in Ukraine, such as the Torpedero clones, the RPS-5 and various arbaletes and spring guns. The Arsenal factory made many guns. Hopefully once the Putin era ends things can get back to normal. I believe Pelengas moved much of their stock and equipment, but I don’t know if they are still operating. The Pelengas store guy is still selling guns, but some are Salvimar models, although a few Pelengas guns are available.
 
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This much simpler drawing lends itself to where the water goes when the gun is cocked to shoot, water being shown in light blue. Air pressure in the tank squeezes the rubber pipe bound at each end onto the multi-ported inner barrel tube and wants to push the spear out. If the water under pressure escapes through the critical seal in the muzzle, which the user will be oblivious to in the water, pulling the trigger will result in no shot and a very exasperated spearfisherman. When the gun works properly it is very silent and ideal for shooting fish in a shoal swimming in a lake.
RPS-3 Original patent drawing wet.jpg
 
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Note that the biasing spring on the "red" sear lever above is of the same type as used here on the final gun. These thin wire leg springs are prone to rusting away.
RPS-3 moving parts and biasing springs.jpg

RPS-3 Original patent drawing firing.jpg

Compare with Omer Airbalete, One Air and Omer XII.
Omer Airbalete operation.jpg
 
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It now appears that the RPS-3 speargun’s most interesting and quirky features, namely the trigger release and sear disk system and the rocking bar self-applying safety lever are not covered in the patent. So now there are two questions. Who designed them and are these features incorporated in the longer 85 cm guns? Seeing as the original Athlete Submariner magazine article diagram shows them you would think so, but the earliest guns that first drew attention to the design may not. They could be like the above patent drawing, but without ever seeing one there is no way to find out. Russian spearfishing forums have not much going on right now, probably due to the current situation, so unlikely to hear from them. Ukraine pretty much the same right now.
RPS-3 original drawings.jpg
 
A photo showing variability in RPS-3 spear tail production. The spear when latched holds on by the tiniest sliver of metal and they will wear out even if the shaft is revolving to a new position each time which spreads the wear around their periphery. The extreme rear cylindrical part has to stick into the boss that plugs the sear disk from the rear or the spear tail will jump over the sear tooth. Think of dangling from a high window ledge literally hanging on by your fingernails! The flash chrome plated shaft on the right easily blisters with rust unless scrupulously cleaned and lubricated and the thin cadmium plated shaft on the left gets surface rust as the cadmium is consumed, but is fixable compared to the chromed shaft which goes into recycling. As the spear tails eventually wear out you get a spare one with each gun. The spear tails are made of hard stuff as they need to be! If the spear clicks into the gun and then promptly escapes your loading hand may still be in the way.
PNC spear tails.jpg
 
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