Taimen - Russian pneumovacuum speargun

How to get all traces of saltwater out of the "Taimen", or anything else that will fit inside the larger tub. Note the barrel cleaning gadget on the top, the muzzle's front section has been removed and is in the smaller box with the line slide.

I prefer the barrel cleaning gadget on left side, when using spear. I find it more convenient for use.
I suppose you have already tested your new toy in sea?

Yes, I have used it in the ocean. The socket mount plastic clamshell rear handle holds water against the alloy rear housing which sits inside it and although the area drains out quickly enough a film of water must stay in there for some time until it all evaporates. Rather than giving any trapped saltwater a chance to cause corrosion I place the gun in the freshwater tub immediately after the dive when I get back to my car (a Subaru 4WD station wagon) and the saltwater is gradually replaced with fresh as the salt disperses in the greater volume of freshwater in the tub. When I get back home I change it all over for another lot of water, but this time the tub is filled right up as seen in the photo and the gun is then removed, the barrel is pumped and then everything is allowed to dry off. The new 2-part muzzle is good as I can remove it by hand and open the front end of the gun up immediately (not on the beach of course), although that may eventually wear the "O" ring out. You can easily inspect the vacuum seal in the muzzle with the front section of the muzzle removed.

That barrel cleaner was first envisaged as being used on the original one-piece muzzle or front hub, but the drilled tube type plastic stem that I expected to use would not be strong enough as the loading effort is sufficient to break it. The gun is not that hard to muzzle load, but like most pneumatic guns it takes a good push to start the piston moving especially if it has not been moved for some time. Maybe I should put more air into it as it is not at the maximum capacity yet, I wanted to get used to using it first.

I removed all traces of grease that I had used earlier to assemble the gun to stop any foreign particles sticking to the muzzle interior, now I just use light oil which floats away in the water, but hopefully nothing ever gets inside there to stick that is of any consequence. I keep the gun up off the sand, I place it on my dive fins if I have to put the gun down near the water's edge. I plan to make a plug for the muzzle, basically a blanked off line slide, to keep wind blown debris out. No windy days so far, very good conditions, but fine sand can blow along the beach and get onto a gun laying on the ground. Normally this is of no concern, but I am not taking any chances with a gun that took many months to arrive here and hence would be just as long a time interval to replace.

The gun is very manoeuvrable underwater, but then so is anything else of such a short length (60 cm, although really a 55 cm).

Returning to the line release, here is a better photo (from the "podvoh" forum review of the gun referenced earlier by Tromic) showing the line release travel stop on the return action, it is a small metal pin. It is this pin that binds on the rubber spring as the line release approaches approximately 36 degrees, as well as the rubber spring folding on itself. It is possible that this pin also prevents the rubber spring element pulling out at maximum forward rotation of the line release lever as when wet the rubber can slide easily inside any restriction given a large enough yank on it, but that is just a guess. Note the neat safety switch in the lower trigger finger guard frame that clicks into a wedge shape recess located in the bottom of the trigger to imprison it.

There is now a new table for the model lengths of the "Taimen" and a nice schematic of the entire gun shown here at post #23:

http://apox.ru/forum/topic/2826-faq-po-ruzhjam-taimen/page__st__20

Note that this is for the 2-part front hub guns and shows the "PVRM" model, so now you can see an official drawing of the rear housing which I had only approximated earlier by modifying the "PVM" diagram. The guns are longer by 6 mm, hence now you subtract 231 from the model designation to arrive at the working stroke or working course of the piston, instead of 225.

I have used the "Taimen" a few times now and I would say that it shoots slightly better than my "Cyrano" of the same size (55 cm), but there would not be much in it. The shaft flies to the end of the shooting line with a just a slight drop towards the end, it zips out of the gun very quickly. The first time I fired it I heard a slight noise, but on listening for it on subsequent shots it seemed very quiet, so maybe something freed up once the gun got working. It seems very accurate, I shot a skinny fish (garfish?) at about 8 feet (visual estimate) with "point and shoot" aiming and nicked the top of his head, the gun might shoot slightly high, otherwise I would have got him (target practice really, just wanted to see if I could do it). With careful aiming it is pretty spot on, although I had a slight offset to the right a few times. I am not a gentle squeeze of the trigger shooter, I give the trigger a quick yank, so I may be turning the gun. The grip handle in the water seems strangely fat in my hand, I feel like I am always trying to close my hand further, the thumb support's lower section keeps my fingers from wrapping on something flat and gives the fingertips the sensation of pushing against a curving ramp, which is exactly what that left side of the lower grip handle is. I thought maybe it was my dive gloves, the grip had seemed OK on land when I first played around with the gun, so I removed my gun hand glove and tried that, but the same sensation persisted. You can live with it, but you are still conscious of trying to improve your grip throughout the dive, which is a bit of a distraction. However this distraction disappears as a victim is spotted and your mind switches to target acquisition.

While you administer the "coup de gras" to your catch the "Taimen" floats muzzle straight down alongside you after you have cast the gun aside, hanging in the water with about a centimeter of the butt poking out through the surface. The white handle shows up very well even in the mistiest conditions, but I thought I had lost it once when a big clump of floating weed collected the gun and pulled it to the bottom by hauling the shooting line down, fortunately I could see the shaft some distance away in the murk and realized that the big clump of weed must conceal the "Taimen" somewhere, so I ripped it apart and there the gun was. A bit of a washing machine in the water that day, surge and currents sweeping stuff around, including me, and very poor visibility.

The "Taimen" is easy to load, you insert the shaft in the muzzle, you can feel the spear tail go through the vacuum cuff, then you click the line slide into position and then push the shaft in with the hand loader. First muzzle load of the day seems hard, then gets easier after that as the piston must tend to stick in storage. The spear alignment control in the muzzle is good with the line slide locking system, you can even shove the loader in with both hands once you get the shaft moving and are starting to tire (well on a short gun anyway), the piston locks with a solid click and a definite stop, there seems to be no rebound of the shaft, I guess that is the vertical action sear column at work.

Line wrapping is quick, but I found that I needed to rotate the line slide to get the shooting line to run on the side I wanted, otherwise the line tended to cross on the side where I did not want it to go and might have impeded the deployment of the line. Normally line slides are loose and can self-rotate, but on the "Taimen" you need to turn it. The line release finger works well, it never had a chance to reacquire any wraps as they are ripped off the gun instantly.

After each shot you need to pull the line slide free of the polyurethane spear tail bush, it seems to stick there rather firmly. The way to do it is you use the speartip floppers as a T-handle to hold the spear with one hand and yank it free by jerking the shooting line with the other, a slight resistance, then the slider pulls free. It becomes a routine after a while, but you can check out your tip while you do it rather than shove it blindly into your palm, you need to look!

I wrapped the shooting line after cocking the gun, the handbook says to do it first, but I don't see the point of doing that unless you had a lot of line on a long gun. I had to untangle the deployed shooting line a few times as weed and swirling water tied knots in it which are always a mystery as to how they are propagated, but are untangled soon enough once you get rid of the weed. This is only annoying when a potential victim watches you do it and then departs as soon as the tangles are cleared for action. The vacuum in the barrel is easy to check, pull the spear out and it snaps straight back into the gun when you let it go while holding the gun horizontally. I applied the safety a few times then did not use it after that (for line wrapping), but a couple of times it seemed to apply itself as I cocked the gun, so I always checked it, you want the forward projection hanging down and not near flush with the bottom of the finger guard frame.

I have not tried shooting the gun two-handed yet, but that is something I do on my long pneumatics to get a more precise shot. Did not seem to be any recoil with the "Taimen", just pull the trigger and the spear zips away in a virtual straight line. I have also not tried the power regulator as I stayed away from the rocks, keeping to the sandy channels, the drifting weed and kelp beds and undulating hillocks of seagrass sections where the roots hold the bottom substrate together. I want a bit of service life from the tips before I risk them around the rocks.

For such a tiny gun the "Taimen" is a surprising performer, but I think the new handle would be an improvement and for me probably the "universal" handle as any thumb support would really need to be better matched to my hand, it is just a size too big for me as I felt like my thumb was barely making it to the correct position. Practice may bring an improvement, I generally shoot a finger grip contoured ambidextrous handle (my Scubapro "Magnum") or a plain flat sided handle (the Mares "2001" type handles).

Intersting impresions! Did you measure the pressure?

tromic said:

Intersting impresions! Did you measure the pressure?

Click to expand...

No, I added air until I could just load it without turning myself inside out. You need to reload when you may start to tire, so I stay below the absolute maximum effort. I never measure the air pressure in my guns, I just look for that loading effort that gives me repeatable results for the gun's shooting range in terms of aiming it consistently. If I need to reach further out then I move up to the next gun size when I return for the next hunt. An easy-loading feature buys a bit more range if the gun has one, but reproducible results and predictability is what you want in any speargun. Water conditions can wear you out, so you need some energy reserve.

Thanks for sharing your experience hunting with the gun. Great info.

I suppose that your Cyrano is wet barrel - and it´s effective length is longer than on the Taimen.

I believe (from looking at the aiming instruction in the manual) that the Taimen shoots a little bit high. Did you aim low as suggested?

Jégwan

Jegwan said:

Thanks for sharing your experience hunting with the gun. Great info.

I suppose that your Cyrano is wet barrel - and it´s effective length is longer than on the Taimen.

I believe (from looking at the aiming instruction in the manual) that the Taimen shoots a little bit high. Did you aim low as suggested?

Jégwan

Click to expand...

The "Cyrano 550" (wet barrel stock gun) has about the same piston travel, I mentioned what it was earlier, so it will be somewhere on this thread. It has a bigger pressure tank and an 11 mm ID inner barrel; the "Taimen" only has a 10 mm ID inner barrel and a way smaller pressure tank, so to match it with the "Cyrano" and maybe do a bit more it is using a higher efficiency operating system to achieve its performance which I think is pretty good. The laws of physics still apply, there are no miracle solutions! Best thing is the "Taimen" floats, the little "Cyrano" sinks like a stone (due to the long snout).

Yes, I remember reading about aiming low, but I was using "point and shoot", I was not looking through the gun's sights. I had watched the shaft fly to the end of the shooting line a number of times and by then thought that I had attained a good idea of where it would hit, seemed to be similar to the "Cyrano", so I used that "calibration". I guess I will have to put in a lot more shots to "scope in" on the "Taimen". On short guns I don't normally use the sights, I lift the gun and when everything looks right (a firing solution is recognized) I pull the trigger. I don't often miss at close range. All the fish I have shot with the "Taimen" so far were sitters, I could have nailed them with anything. I was looking for a King George Whiting, but visibility was poor, so I saw none. Being a moving target they are more of a challenge as you estimate an intercept course while they are slowly cruising, if they put on the gas you can forget about it as they flee at Warp 8.

What might be a compression ratio of Taimen? Cyrano 850 has it about 1.15, as I recall.

So the small Cyrano is a sinker - that's why the Russians put polystyrene floating elements on them...

Yes there's this quite funny picture in the manual where the inventor of the gun aims (a dotted red line) at a fish silhouette drawn outside the photo.

I've heard that the King George Whiting is a strong, fast and delicious fish. Hope to see a photo, in the near future, with the Taimen on top of one in same length

Jégwan

Well I hope to shoot one, but first I need to find one as only grass whiting were visible on my last visit, not a sign of the King George Whiting anywhere, but the visibility was abysmal.

To answer Tromic's CR question the shortest "Cyrano" gun has a higher compression ratio as the "Cyrano" nozzle removes proportionally more of the cylindrical tank for that gun's length, but I have never worked out what the CR figure is. It is an easy gun to load and good to shoot, but you have to tuck it under your arm or have it on a tether if you don't want it bouncing around on the bottom. I don't know what the "Taimen" gun's CR is, but the ratio of the cross-sectional areas of the inner barrel and tank may be a guide.

Here are some maintenance comments:

The "Taimen" shafts and speartips do need oiling after washing off any saltwater residues. I found that if I just put them in freshwater and left them to soak that they developed brown tarnish marks which are the first signs of corrosion, just a tiny spot here and there and around where the threaded speartip had previously overlapped the shaft. A rub with WD40 soon removed these tarnish marks, so the shafts and speartips need to be washed, dried off and then oiled, don't leave them wet overnight like I first did. I also put some oil in the muzzle and worked the spear up and down to lubricate the inner barrel after doing the same with freshwater. By first removing the vacuum cuff and reassembling the hub without it you don't really need the cleaning bottle gadget to do this, the 2-part hub body without the seal installed can hold fluid up to the level of the 4 small side ports before it runs out of them with the muzzle held upright. I later pushed the inverted gun down on the shaft with the shaft's threaded tip engaged in a drilled hole in a large block of wood so that anything inside the inner barrel run out around the face of the held back piston, then I removed the front section of the hub to empty it out with the gun still inverted. This cleaning may not be entirely necessary, but by doing it there should be no surprises for saltwater only spearfishermen like myself. Some stainless steels are less stainless than others and the inner barrel is stainless as is the shock absorber body, but what type I don't know, so better to be safe than sorry!

It is a quick job, probably took longer for me to write about it here than to perform it.

tromic said:

What might be a compression ratio of Taimen? Cyrano 850 has it about 1.15, as I recall.

Click to expand...

I calculated the "Taimen" compression ratio as being 1.17 if we neglect the air volumes in the rear housing and assume that the working course of the piston is equal to the effective length of the tank or air reservoir. That means the compression ratio equation (refer http://forums.deeperblue.com/threads/pneumatic-speargun-compression-ratio.86054/) CR = initial volume divided by final volume or (Vb + Vr)/Vr = Vb/Vr + 1 can be simplified to the inverse of CR or 1/CR = 1 - (rb/rt)^2.

Note that the total internal capacity or volume of the gun Vt = Vb + Vr. As Volume V = Area A x Length L of the reservoir and A = pi x r^2 then we can cancel L and pi out of the fraction and algebraic manipulation produces an equation containing only the radii of the respective volumes, i.e. the inner barrel volume and the total internal volume of the gun determined by the tank ID. I have derived this inverse CR equation on another thread here, but cannot remember which one.

rb is the radius of the inner barrel, which equals 5 mm.
rt is the inner radius of the tank, which equals 13 mm. [I used rt rather than rr for the reservoir (or tank) just so we don't get confused]

Therefore the compression ratio of the "Taimen" is 1/(1 - (rb/rt)^2) = 1/(1 - (5/13)^2) = 1/(1 - 0.148) = 1.17

If we take a regular "Sten" then the radius of the inner barrel is 6.5 mm and the inner radius of the tank is 19 mm. Making the same assumptions, although the "Sten" has a nose cone internal volume and a regulator block which will depart from the simplifications being made here, we obtain a compression ratio of 1/(1 - 0.177) = 1.13 which is about right. For the "Cyrano" we have to adjust the equation as L for the inner barrel is longer than that for the tank due to the snout or nozzle removing 17 cm from the tank length of each "Cyrano" gun which changes the CR for each gun length, shorter guns being affected more than longer versions.

Well done Pete! So CRs for Mares and Taimen are very close. I remember when I had my first pneumovacuum speargun Sraga sub Pilco mini 40 cm (long time ago) it was difficult to finish loading it because of higher CR than on other brand, water barrel, pneumatic spearguns like Mares. That speargun had inner barrel 13 mm ID and outer barrel about 35 mm ID? ... (not sure). At that time I knew next to nothing about pneumatic spearguns. I used it with 9 mm shaft with prongs on 1.5 mm effective range. It was pretty effective for such a short gun.

Yes, high compression ratio pneumatic spearguns can be difficult to latch, I remember a monotube speargun that had a compression ratio of 2.0! Of course you have to pay attention to the initial charge pressure with very high compression ratio guns. An example would be the RPB-1 which has a compression ratio of 1.33 as it has a 14 mm ID inner barrel and a tank ID of 28 mm. The 11 mm ID inner barrel "Taimen" must have a compression ratio of 1.22, it shoots an 8 mm spear.

Maybe a bit more accurate equation would be if you take the inner barrel wall thickness in account too. Is is about 2.5 mm for Mares like guns. Than the CR would be even higher.

tromic said:

Maybe a bit more accurate equation would be if you take the inner barrel wall thickness in account too. Is is about 2.5 mm for Mares like guns. Than the CR would be even higher.

Click to expand...

The barrel wall on the "Taimen" is very thin, the inner barrel tubing starts off at 12 mm OD and 10 mm ID, then they machine away half the thickness of the barrel wall! At 0.5 mm it was not worth worrying about for the CR calculation.

I have spoken about the "Taimen" having a big rear grip handle, here you can actually see how large it is compared to a selection of other speargun models. The flowing and curvy styling makes the "Taimen" grip handle not look out of place on its small receiver (or tank), at 28 mm OD it has the smallest body tube shown here, with the "Aquatech" being next at 30 mm OD. For its size the "Aquatech" is the heaviest gun here, being a hydropneumatic model and as such a dedicated sinker, while the "Taimen" is easily the lightest gun thanks to all the elaborate machining away of surplus metal, which is what makes it an expensive gun to produce. As I had speculated long ago it is an (automatic) wristwatch amongst an arsenal of alarm clocks, but now I know it to be so having eventually got my hands on one, thanks to the "Taimen" Company who persevered in sending it halfway around the planet to the land of OZ.

tromic said:

Maybe a bit more accurate equation would be if you take the inner barrel wall thickness in account too. Is is about 2.5 mm for Mares like guns. Than the CR would be even higher.

Click to expand...

If taking in account wall thickness (2.5 mm) for Mares like spearguns CR is about 4 % higher.
(using Pete's formula CR=Vb/Vr + 1)
For my Pilco Mini 40 it would be 1.19 (instead of 1.14).

Actually I had rounded the "Taimen" result as the CR calculation produced a figure of 1.174 (to 3 decimal places) and by including the inner barrel wall this raised the value to 1.181, a difference of 0.007 which is 0.6% of 1.181, so not significant when we have neglected the small volumes in the rear housing's airflow passages. The "Taimen" has no nose cone internal volume, unlike many other pneumatic spearguns and which will also have some effect on the CR value, but the contributions tend to cancel out when we over estimate some things and neglect others. An absolute value for the CR is not really essential, we just need the CR value to a certain degree of accuracy to distinguish it from other gun constructions. I know from someone else's work (on his "fusils.xls" spreadsheet from memory) that the "Sten 110" 13 mm inner barrel gun has a CR of 1.13. He actually calculated the volumes of the tank producing an initial (unloaded) volume of 971.88 cc and a final (cocked gun) volume of 845.79 cc. The internal (swept) volume of the inner barrel was stated as being 126.10 cc. He states that the variation in gun volume is 13%. A number of different guns were subjected to these same measurements and the necessary calculations made for a ballistics mathematical model, including the "Cyrano", but for the moment I cannot find the "Cyrano" page (I had printed them all out, unfortunately I no longer have the spreadsheet file).