Re: Hydro/pneumatic gun: adjusting the trigger
One of the problems that users of the RPS-3 spearguns found when shooting their guns was that the line release would not always release, thus causing the shooting line to unexpectedly snap. The spear would then promptly disappear into the weeds on the bottom never to be found again, or the wounded fish swam away with the spear also resulting in its loss. This only happens if the trigger and line release operation are not properly synchronized and the adjustment is easy to do once you know how to do it.
The RPS-3 user handbook strongly advised gun owners not to make any changes to the adjusting screw in the face of the small internal boss that controls the sear release action, but that is exactly how you adjust the gun. The correct adjustment is obtained when the small diamond or lozenge shaped pivoting lever in the rear of the gun frees the line release lever before the boss pulls out of the rear of the sear disk, as the boss clearing the rear face of the sear disk causes the gun to shoot. Turning the adjusting screw anticlockwise effectively lengthens the screw and delays the sear release action, turning the screw clockwise shortens the screw and makes the sear release earlier when pulling the trigger. To get it right you need to use a "trial and error" approach, but it does not take very long to carry out.
A wetted spear (for muzzle seal lubrication) is loaded into the gun with the hand pump's removable Tee-handle replacing the speartip (it has the same screw thread, in fact the hand pump rod is a spare spear shaft), that way you have complete control over the gun and the spear when using both hands. No significant amount of water, beyond wetting it down first, is to be present in the inner barrel, as for this test we just use compression of the existing air in the inner barrel.
You grasp the gun's pistol grip handle with your thumb curled over the top of the rear of the gun and pressing firmly on the back of the line release finger sticking up vertically at the top rear of the gun. When you pull the trigger back slowly you will feel the line release lever suddenly move under the pressure of your thumb and only after this happens should the sear tooth release the spear, your hand on the Tee-handle will feel the spear being released due to the slight air pressure in the inner barrel created by your loading action weakly driving the spear forwards. If this does not happen and the sear releases first then the front adjusting screw has to be lengthened to delay the sear release action, so you unscrew the gun's rear handle section and turn the adjusting screw head in the now exposed boss (seen when looking in from the front of the detached rear handle section) half a turn anti-clockwise and then reassemble the gun to try it again. You repeat this procedure until you get it just right. If you overshoot the correct adjustment the line release will free too soon, but this is preferable to it being too late or coincident with the shot. To go back the other way you just progressively use half (or quarter) turns of the screw going clockwise which shortens the screw and causes the sear release action to happen sooner. It may sound complicated, but the mechanism will not be out by much, so not many turns of the adjusting screw are required. There is a similar rear screw that pushes directly on the diamond shaped lever, accessible from outside the gun once the black plastic grip handle is removed (undo the large "cheese head" nut with the pivoting metal attachment loop located in the handle butt), but you rarely need to adjust it as it is jammed by a twisted metal element built into the sliding rod it projects out of. You only need to adjust it if the safety device is not being pushed by the rear of the trigger hook when you fire the gun (this is mentioned further on), but any final adjustment must be done with the front screw, which the small internal boss actually slides on, until the screw's head catches it internally to pull the boss back.
When you have it set just right this is what happens. Pulling back on the trigger the line release finger frees, the back of the trigger hook causes the safety device to flip back to the horizontal "safe" position and only then the gun shoots. When you reload the gun the small internal boss moves forwards to trap the sideways displaced sear disk (a strong internal coil spring is pushing the boss which plugs the disk once it centralizes in the gun body, thus gripping the spear tail). This boss movement pulls on the trigger mechanism's long internal sliding rod via the front adjusting screw's shank, the front and rear adjusting screws both thread into this long sliding rod, to cause it to come forwards and that in turn drags the trigger hook forwards causing a short horizontal tab on the trigger's rear face to pull out from under a transverse metal strap on the gun's pivoting safety device. Once the rear tab on the trigger slips out from under this transverse metal strap the latter falls in directly behind the tab thus blocking the trigger from moving backwards. That is how the RPS-3 speargun automatically applies the safety each time you reload the gun, which is very ingenious. When you shoot the gun you cause the safety device to initially reset partially and actually cocking the gun later completes the movement to the full "safe" position. A brilliant piece of engineering, but bought at the cost of tiny wire loop leg type springs and a number of small pivot pins (their diameter is only 2 mm!) and an elaborately machined (turned, multi-axis milled and multi-bored) rear alloy housing to contain it all. To unblock the safety you push with your trigger finger on the downward curved metal tab in front of the trigger hook that looks like a second trigger and that causes the safety device, which the downward curved tab is actually connected to, in the form of a pivoting bar to swing downwards at its rear end to clear the trigger for shooting. The safety device pivoting bar has two set positions governed by an "over the centre" action of its looped wire biasing springs situated on either side, it is either hanging down on a slight angle ("fire") or up and horizontal ("safe") at its rear end. The front of this bar (which is a stamped or folded metal "U" cross-section) pivots at its front end, just where the curved actuating tab which is integral with it descends directly in front of the trigger.
None of this layout was cheap to make and probably very time consuming to assemble, so how the manufacturer ever made any money on a gun that sold for only 55 rubles is hard to fathom, but one can understand the attraction of such a highly engineered weapon of very attractive, albeit diminutive, proportions. In a sense its rival is the "Taimen", both guns using vertical release action sear teeth (no sear pivot pins are used) and small diameter body tubes (30 mm), but one sinks and the other floats, which is also how their respective fortunes as spearfishing weapons has progressed. The simplicity of the "Taimen" trigger mechanism and its elimination of fiddly adjustments (that advantage is stated in the "Taimen" user handbook) is a direct reference to the RPS-3 speargun's trigger mechanism tribulations for owners who failed to understand how their guns worked and were too easily convinced by the handbook not to experiment. Having lost their spear they were out of action and if they never fixed the trigger adjustment then the spare spear, taken out of the hand pump, probably soon joined its comrade slowly rusting on the bottom.
One of the problems that users of the RPS-3 spearguns found when shooting their guns was that the line release would not always release, thus causing the shooting line to unexpectedly snap. The spear would then promptly disappear into the weeds on the bottom never to be found again, or the wounded fish swam away with the spear also resulting in its loss. This only happens if the trigger and line release operation are not properly synchronized and the adjustment is easy to do once you know how to do it.
The RPS-3 user handbook strongly advised gun owners not to make any changes to the adjusting screw in the face of the small internal boss that controls the sear release action, but that is exactly how you adjust the gun. The correct adjustment is obtained when the small diamond or lozenge shaped pivoting lever in the rear of the gun frees the line release lever before the boss pulls out of the rear of the sear disk, as the boss clearing the rear face of the sear disk causes the gun to shoot. Turning the adjusting screw anticlockwise effectively lengthens the screw and delays the sear release action, turning the screw clockwise shortens the screw and makes the sear release earlier when pulling the trigger. To get it right you need to use a "trial and error" approach, but it does not take very long to carry out.
A wetted spear (for muzzle seal lubrication) is loaded into the gun with the hand pump's removable Tee-handle replacing the speartip (it has the same screw thread, in fact the hand pump rod is a spare spear shaft), that way you have complete control over the gun and the spear when using both hands. No significant amount of water, beyond wetting it down first, is to be present in the inner barrel, as for this test we just use compression of the existing air in the inner barrel.
You grasp the gun's pistol grip handle with your thumb curled over the top of the rear of the gun and pressing firmly on the back of the line release finger sticking up vertically at the top rear of the gun. When you pull the trigger back slowly you will feel the line release lever suddenly move under the pressure of your thumb and only after this happens should the sear tooth release the spear, your hand on the Tee-handle will feel the spear being released due to the slight air pressure in the inner barrel created by your loading action weakly driving the spear forwards. If this does not happen and the sear releases first then the front adjusting screw has to be lengthened to delay the sear release action, so you unscrew the gun's rear handle section and turn the adjusting screw head in the now exposed boss (seen when looking in from the front of the detached rear handle section) half a turn anti-clockwise and then reassemble the gun to try it again. You repeat this procedure until you get it just right. If you overshoot the correct adjustment the line release will free too soon, but this is preferable to it being too late or coincident with the shot. To go back the other way you just progressively use half (or quarter) turns of the screw going clockwise which shortens the screw and causes the sear release action to happen sooner. It may sound complicated, but the mechanism will not be out by much, so not many turns of the adjusting screw are required. There is a similar rear screw that pushes directly on the diamond shaped lever, accessible from outside the gun once the black plastic grip handle is removed (undo the large "cheese head" nut with the pivoting metal attachment loop located in the handle butt), but you rarely need to adjust it as it is jammed by a twisted metal element built into the sliding rod it projects out of. You only need to adjust it if the safety device is not being pushed by the rear of the trigger hook when you fire the gun (this is mentioned further on), but any final adjustment must be done with the front screw, which the small internal boss actually slides on, until the screw's head catches it internally to pull the boss back.
When you have it set just right this is what happens. Pulling back on the trigger the line release finger frees, the back of the trigger hook causes the safety device to flip back to the horizontal "safe" position and only then the gun shoots. When you reload the gun the small internal boss moves forwards to trap the sideways displaced sear disk (a strong internal coil spring is pushing the boss which plugs the disk once it centralizes in the gun body, thus gripping the spear tail). This boss movement pulls on the trigger mechanism's long internal sliding rod via the front adjusting screw's shank, the front and rear adjusting screws both thread into this long sliding rod, to cause it to come forwards and that in turn drags the trigger hook forwards causing a short horizontal tab on the trigger's rear face to pull out from under a transverse metal strap on the gun's pivoting safety device. Once the rear tab on the trigger slips out from under this transverse metal strap the latter falls in directly behind the tab thus blocking the trigger from moving backwards. That is how the RPS-3 speargun automatically applies the safety each time you reload the gun, which is very ingenious. When you shoot the gun you cause the safety device to initially reset partially and actually cocking the gun later completes the movement to the full "safe" position. A brilliant piece of engineering, but bought at the cost of tiny wire loop leg type springs and a number of small pivot pins (their diameter is only 2 mm!) and an elaborately machined (turned, multi-axis milled and multi-bored) rear alloy housing to contain it all. To unblock the safety you push with your trigger finger on the downward curved metal tab in front of the trigger hook that looks like a second trigger and that causes the safety device, which the downward curved tab is actually connected to, in the form of a pivoting bar to swing downwards at its rear end to clear the trigger for shooting. The safety device pivoting bar has two set positions governed by an "over the centre" action of its looped wire biasing springs situated on either side, it is either hanging down on a slight angle ("fire") or up and horizontal ("safe") at its rear end. The front of this bar (which is a stamped or folded metal "U" cross-section) pivots at its front end, just where the curved actuating tab which is integral with it descends directly in front of the trigger.
None of this layout was cheap to make and probably very time consuming to assemble, so how the manufacturer ever made any money on a gun that sold for only 55 rubles is hard to fathom, but one can understand the attraction of such a highly engineered weapon of very attractive, albeit diminutive, proportions. In a sense its rival is the "Taimen", both guns using vertical release action sear teeth (no sear pivot pins are used) and small diameter body tubes (30 mm), but one sinks and the other floats, which is also how their respective fortunes as spearfishing weapons has progressed. The simplicity of the "Taimen" trigger mechanism and its elimination of fiddly adjustments (that advantage is stated in the "Taimen" user handbook) is a direct reference to the RPS-3 speargun's trigger mechanism tribulations for owners who failed to understand how their guns worked and were too easily convinced by the handbook not to experiment. Having lost their spear they were out of action and if they never fixed the trigger adjustment then the spare spear, taken out of the hand pump, probably soon joined its comrade slowly rusting on the bottom.
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