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Birth of EDgun

Hey all,
I have dug this documentation out of the Russian blog archives as I thought is was not only an interesting read and worthy of sharing but worth documenting in English to protect it and make sure it is never lost in time.
I spent a lot of time translating it from Russian to English, although my translation is not perfect I hope you can understand most of it and enjoy the journal of a younger Ed with his evolving journey building the first “RCD” which eventually evolved into the Edgun matador we know today. Regards, Wingman

On this page we will tell you a little about the RCD rifle, made independently. Many technical solutions used on this rifle are imperfect and require improvement, but, nevertheless, it works and will serve as a kind of testing ground for further development. And the fact that they will, we do not doubt it, because the process of inventing, making and using it turned out to be impossible and interesting.
First a little background: the thing is that the hobby for pneumatics has been going on for me for more than two years, at first there was an MP-654K, then it was upgraded, then I bought an MP-512 plus a VOMZ optic 4x32L, then an upgrade, then Gamo Hunter turned up on it optics with MP-512, Gamo Hunter got to me in a terrible state so I had to upgrade it. All upgrades and other my ideas were reasonable and not very selflessly helped me to realize my friend Nikolai, a highly skilled metalworker, with his help many ideas came to my head. And without it all this would remain only in my head and in my dreams Thus this rifle is the result of the work of our small team. All the time during which I was “sick” with pneumatic fever, I enthusiastically read the conference on AirGun.ru and reading about the exploits of ANDY with a rifle I wanted the same, but the financial condition of the family did not allow me to spend a lot of money on a hobby. Then I read the article by Demian “Doing PCP” and just caught fire with the idea of making a PCP rifle. I started designing, I did not know anything about it. Nicholas agreed to enter the project, initially foreseeing all its severity, repeated reworking of details and other charms. We must give him credit – in many respects he was right, and that is why I so appreciate his patience and endurance, which allowed us not to give up everything halfway. At first they decided to make a rifle with a reducer, and even made some details, but after some doubts.
General form.
The period from the beginning to the end of the manufacture of the rifle lasted more than 4 months, but this is not a clean time of manufacture, the fact is that the rifle was made during our free time, so we could not afford to devote ourselves entirely to it. In addition, as the whole new process took some time to study the subject. In general, one way or another, but the first field shooting was held in June 2002, which showed us the advantages and disadvantages of the resulting unit. The first field shooting, the rifle is not painted yet.A brief description of the components of the construction (in ordinary type, this is what I wrote right after the tests, italics are what I’m writing now)

1. Barrel: I took from my old MURK 512, and what should I do? It was not for the GC440 to disassemble for the experiment, the result of which was not clear until almost the end. The barrel was pressed out of the breech, made a tube into which the barrel was pressed into a hot barrel. The tube had to be made, since the diameter of the barrel (13 mm.) seemed to us not very large in order to insert the tube coming from the valve into its side.(It was done so that the barrel does not go out to the end of the tube, but a hole is drilled in the tube, such as a breech, but I missed the calculations and said that we need to make a hole with a diameter of 5mm. Moreover, we have a transfer tube from the valve to the barrel a large diameter – as a result of a bullet stuck in this wall when loading, if Diane Rastatt still passes less, then the GC just crumples into a flat cake. It is necessary to charge a little by turning the rifle. That’s why I had no specialty until I understood what was happening. ) (To date, on September 5, 2002 to load I have already adapted myself, I do not have any problems and do not affect the accuracy).
2. The air reservoir: Initially, it was a pipe from Steel 20, which I found in the boiler equipment repair shop. As the pipe went for boilers, the GOST was at least respected, I would like to believe, in its manufacture. For each bundle of pipes is a quality certificate, they decided to believe it. The outer diameter of the pipe was 38 mm, the wall was 4 mm, it was slightly turned over the outer diameter, it was calculated that it would withstand a pressure of more than 400 atmospheres with a 2-fold margin of strength. Pressed with water at a pressure of 350 kg / cm2, nowhere of any water seals flowed. We kept this pressure for a couple of minutes, the pump pumping water, began to suffocate, turned off, counting the tests as successful. In subsequent versions, there is a thought of using a tube of another steel, more suitable for these purposes, so that you can make walls thinner, smaller weight …
In the workshop, during the manufacturing process, it is evident that the tank is primed on an adhesive tape. (Now the tank is redesigned, the same pipe, but the principle of fixing the front and rear plug is changed, before that it was carving and sealing on the end.) Because of the carving, the plug was always pushed up at different angles, the carving was pulling, by the way Nikolai was initially against carving, and there were problems with the installation of the charging valve.This now made the plugs with a ring groove for the ring in the depth, and the fixing on three bolts M5, with the head with an internal Allen key (thanks bricks20 for photos of his LOGAN, the idea from there “liked”). It is estimated that one bolt is enough for this pressure, and we have three, and the process of assembling the disassembly was much easier and aesthetically more pleasant. “After that, they all again poured water – without problems.” On the next rifles, I bought a stainless steel tube 32×3 , steel 12H18N10T.)

3. Manometer: a normal manometer, military, judging by the scale, it glow in the dark, then another friend saw the manometer, asked where we got the manometer that they had in the Army, in the missile troops. The manometer is calibrated to 250 kg / cm2 with the division rate of kg / cm2. Outer diameter 40 mm, less would be more desirable, but where to find?
4. Valve: made first with a ball, but either the ball was curved, or something else, but the gasket constantly tore off and the ball wedged. We decided to replace the ball with a plunger closing the valve on the end. Works, for now. Just in case, they made a cork with a gasket, after charging, tighten the stopper, and thread the ends and in case of which, through the gasket, it will not squeeze.(We are not happy with the operation of the charging valve, but we will not change it yet, but do not touch it yet.) (For today, September 5, 2002, the charging valve has already been changed, the entire design of the front plug has been changed, the charge is made using a quick-detachable connector, no threads, ten seconds and the rifle is recharged.The valve works fine, no complaints).

5. The valve final: a long time, they did not manage to do everything and the stem was thin with o rings on it, and then it dawned – to make the valve in two parts! At once everything fell into place, both literally and figuratively. The valve is centered on two surfaces, along its liner, on which the spring presses and which runs precision in the well where the spring stands and on the rod, on which the striker strikes, a rod with a diameter of 2 mm passes through the wall of the valve body without any o rings and nowhere binds, done with precision. The outer diameter of the valve seat is 8 mm. We thought that it would be very difficult to open, but it turned out that only a small impulse is needed to open it, and then it opens itself.(The valve was reworked four times until it was more or less stable, now we have a similar design, but the diameter of the valve is reduced to 7 mm, the diameter of the opening is 4.5 mm. The guide coil, with holes, acts as a kind of buffer, bricks20 , wrote that he had a similar detail in his LOGAN, a volume of 4-5 cm3, with an inlet from the reservoir of 3 mm.We play the role of such an opening gap between part 9 and detail 6, the gap is very small, so that it turns out that The end of the valve itself is made conical, meaning its internal part.The valve behaved unstably until it “stuffed” itself saddle. Now let’s look atskolko enough gasket 10.) (For today, September 5, 2002, this valve is also redesigned, the design is different, “shot” from him more than 10 thousand shots, dismantled, looked, no trace of work. Good turned out).

6.The stock :I know, I know, do not scold, the wood I took is not the best. I had difficulty finding a birch board 50 mm thick, this one has internal knots, but had to be made from it. The internal inletting groove was cut on a milling machine, then manually adjusted, then with the help of a blunt knife and files which I used to make my guns as a child about 20 years ago, gave the bed some form. Although I first drew the whole layout of the rifle on a sheet of paper on a scale of 1: 1, and then around it began to describe the stock, there were several options, I chose the most successful, in my opinion. In general, the entire bolt group had to be removed inside, but when milling, some of the wood was chipped off and had to make changes along the way.
Naturally, the next rifle will be much better, I’ll find a good birch board, or beech (As for the beech, I got excited, its specific gravity is slightly higher than that of the birch, but the density is better. By the way, I already bought 4 beech planks for stocks, the next rifles will be with beech stocks). (we started making a stock, on September 5, 2002, the wood is really SUPER !!! The stock turns out beautiful and elegant, so Nikolai is stingy for praise, but when he saw it he praised me very much
Almost ready, but still no handle and butt plate

.7. Rings of the stock attachment to the tank: I really like them, they are made neatly, thinly, but firmly. First, on a milling machine, then on an emery paper, then with a file, then with a sandpaper. In my opinion this is the best part of this rifle. (And now I still think so :-). The part that did not deliver any problems.)


8. Handle for fixing the optics: they did not do it themselves, they ordered it in another shop, there was not any more time, and the guys there also did a pneumatic gun.

To their happiness, they could not make a valve, so all this was abandoned. Why for happiness? Because they are simple working guys, not burdened by the notion of the need to calculate such designs, so I’m sure for the air cylinder they would take the first pipe they got, without crimping (they were surprised to learn that we did it) would destroy it and the rifle probably after the first attempt to pump it up.
To the accident history at the plant, one more incident would have been added. Even such a simple thing, like a drawing they could not do normally, they messed up the dimensions, it was necessary to adjust it in place. Well at least a router was found for milling a dovetail and thanks for that. The dovetail however I did not trust, although they were very torn. We first welded the handle to the rings, with argon, then we removed the welding with the face milling cutter. Have exposed the handle on the milling machine taking for a basis a barrel, and in parallel a dovetail. Everything turned out as in the best houses of Paris and London. Horizontally parallel to the stock, vertically, 2mm are lined up at a length of 200 mm towards the barrel that is, the breech will be raised relative to the barrel by 2mm, I think that this is not very much.(The fire did not reveal any problems).


9. Hammer: metal cilinder, with a handle for the catch of the bolt. we started with the spring from an umbrella, but it was very tight, then found softer. Seems to be OK. In general, you can make the spring even softer, the impulse for the opening of the valve was needed to ridiculously small. (I also had to tinker with the hammer, I lightened it, and then worked out the optimal length of the spring which took a long time … Well, we already had a chronograph, with it all settings were made much easier.)
10. Trigger: assembled on a demountable shoe, with two adjusting bolts. Adjustable length of the trigger and free running first stage. The release is very soft, at first it was very long. When I first tried it, Nicholai, seeing as I press it, said that he would go for a smoke, maybe I’ll have it fire in the evening.
Adjusted, everything is normal, the movement is not long, at the end there is an obvious “stop”, in front of the shot, in my opinion, it is convenient. Although Nikolai says that he does not like that the first stage is too easy, well, you can put the return spring of the trigger more potent and will be tight. Everything is made from Steel 45, then hardened and polished. Three times everything was reworked until he got a clear job.(Actually, the adjusting bolt is only one, the second one I broke, twisting it :-). for me, one detail has broken, has croaked, then has made new, now like all is normal. I agree with Nikolai – the descent is too soft, I should make it tougher, I think we need to start by restoring the second adjusting bolt. In the next rifle, there will be a completely different scheme, everything will be removed into the pipe.)
11 Bolt: a bolt , a handle, a bullet pusher, a rubber o ring for sealing, there is a lug on the bolt that hooks the hammer and cocks it, then, after closing the bolt and turning it, it enters the conical groove and locks the bolt with interference. First there was the idea of making a platoon through a lever with a variable shoulder, that is, the more the spring contracts the more lever arm and the force of the cocking practically does not change, but after we realized that a powerful spring is not needed we decided to simplify the circuit. (They did not change anything, everything suits).
12. Sound moderator: without it it is terribly loud, had to do it.
Inside, five partitions, planted on three spokes, as in PBS for Kalashnikov, the sound-absorbing material is wound on the spokes. The diameter of the hole in the partitions is 6 mm. (I also had suspicions that he was slowing down the bullet, although the speed of the exit from the muffler was more than 300 m / s). (For today, September 5, 2002, the sound moderator has been shortened, it shoots a little louder, but the power has increased, noticeably).
It can be seen that the bolt is not completely tightened up, the keys are worn, tore off the hexagon on the bolt, and never tightened it up to the end :-). Seen advantages: 1. The stock is very comfortable, but it’s made for the left handed, but the people say that it’s convenient to shoot with the right one. The only thing, the psychological discomfort for them, that the loading window is just under the cheek, but what to do ?!
In the car with this rifle is very convenient, with the GC 440 can not even compare, with a quick hover on the target it is not very light, 5 kilograms, more than this you are not huhry-muhry. (I have a problem – when shooting, the butt is pressed against the chest in the region of the heart – from the beating of the heart it “beats” horizontally. Now I’m used to – a clear improvement). 2. The trigger pull is soft, easy and predictable.(Now I think a little bit differently). (The descent adjusted so that at the very end there is a click indicating that there will be a stall now, very convenient, September 5, 2002) 3. The weight is slightly more than 5 kg, well balanced, the center of gravity is in the region of 40-50 mm. forward from the trigger. 4. The hook on the backplate improves the aiming and holding of the rifle.
5. Rubber pad on the butt protect against slipping rifle on clothes. (So this pad was not finished, but it would be necessary … While it was necessary to wrap up the tip, so that the clasp does not slip on the clothes).
Observed shortcomings: 1. Adjustment of the trigger is inconvenient, it is necessary to disassemble everything in order to change the adjustment. In the following models, everything will be done more ergonomically. Although, on the other hand, it once adjusted what’s to gain there ?! 2. It’s ugly that you can see a hole in the back of the butt, but this is an industrial fault, in the following models it will be avoided. In general, I do not like round bevels on the stock, I’ll try to make it more accurate in the following models. 3. The fill line union nut is a convenient matter, but I would like to have a quick-release fitting, we will think in this direction. (I’ve also got used to the nut and we’ll make the outfit for the next rifle.) (The changeover was made, now quick-detachable, convenient and reliable, September 5, 2002.) 4. A smaller-diameter manometer is desirable, this one is painfully bulky.
Back wrapped tape, there are no rubber pads.
5. Weight for hunting hunting is not the lightest, but it is treated with either a strap or a shoulder strap on the butt. Although the “commercial” version, there are still opportunities to reduce the weight by 30%. 6. With the riser rail and optics, the dimensions in height are not that small. (The length from the tip of the stock to the tip of the muffler is 785 mm, from the bottom of the pistol grip to the turret of vertical corrections on the scope is 310 mm.)
7. The port for loading is not that big, it is not very convenient to load it in a hurry. There is an idea to make a window so that you just need to put a bullet in it, without getting inside, and it would be pushed by the bolt itself. (Actually, I’m already used to it, I charge it quickly, but for the right-hander it’s inconvenient, it’s a fact).
8. There is no safety catch, no trigger guard, no manual. The accidental firing is protected by the design of the trigger descent itself, I even figured with a hammer, so that it would fall off with a sear, it would sit like a glove. Maybe on the following models it will have one. (There was one accidental discharge with a bullet in the barrel, but this is not a problem of the mechanism, but a lack of a safety catch and guard around the trigger.)
I put the rifle on my knees and “kicked” my foot onto the trigger, the bullet shot out and hit inside the car door. I did not go out, reloaded, killed a crow, and then went out to look.The door of the car was saved only by the fact that the bolt was not closed so air escaped, the bullet did not exit, it got stuck somewhere inside, and maybe hit something solid, a mechanism of some sort. , I’ll see.)
9. The distance between the barrel and the the handle is not very large, it is not convenient to use it as a carrying handle. In the following models, the rail may be made as a separate part, then it will be necessary to make a little higher the handle and then it will be convenient to carry it by it. (I can not stand it, I take it under the stock and I carry it like this.) 10. It’s not very convenient to cock due to the location of the bolt near the shoulder, you have to move the rifle forward. There is an idea to make the shutter rotary with the locking of one combat lug in the body of the bolt frame, with the drive from the handle located in the holding handle area.(I’ve already got used to it, I’m charging it fast, but the idea with such a shutter still lives.) (The idea with such a shutter has already died, it will be similar, but with the possibility of quick alteration, in the field from “right-handed” to “left-handed” and back, September 5, 2002 of the year)
They wanted to shoot with optics, removed from the sold GC 440 VOMZ 4x32L put on the pilot version, made three shots at a cardboard box at a distance of 17 meters (measured rangefinder, Ingvar had, did not put on later so that the optics did not rebuild, then GC 440 did not to shoot again, so no longer fired at further distances) Yap-Yap bullets (nothing the French can not do normally) the spread was an even triangle of the order of 8 – 10 centimeters. I was very upset, I knew that these bullets were shit, but not to the same degree. And I thought then that something was wrong with the rifle. But he decided to shoot with lighter GCs. He shot three shots, the bullets lay in the same triangle, but practically next to each other, between the edges of the holes was a few millimeters. I must say that I shot from the top of the door off my knees, which in itself is uncomfortable, (I usually rest on the roof), my friend, a turner with his son, was sitting in the car and they enthusiastically moved around so the car wasnt completely still, plus the sight was a new one, I did not have clear picture, though I also tried to adjust it. In general, the conditions for shooting were not ideal.
Then three more shots, scattered slightly more than the GC, but I was still in an uncomfortable position when firing. CP 10.5, which I sent Hans I did not shoot, I’ll use them for shooting with a chronograph, which Sergei seems to have done and I believe he is already on his way to me.
They started shooting at every piece of garbage, they shot at the city dump, there were targets in excess. Homeless people approached, (Now the rifle is equipped with BSA 6x24x40 optics, MilDot grid, with podstvetkoi.Thanks bricks20 for “aiming” at the sight.Rings B-Square, adjustable, I like .The sight and rings are happy, the adjustment is clear, although Buka in St. Petersburg said that the adjustment 1/8 MOA is not very convenient, you will not hear a click until you have reached it, we have a strong wind, there is no way to shoot a rifle at all distances, while at a distance of 50 meters, while shooting from a car, I easily stack all bullets in a circle diameter of 30 mm, and I see that the grid goes to the target. In any case, with an unstable emphasis on this distance to get into the neck of a vodka bottle is not a problem. I am satisfied with the sturdiness, although I would not refuse a Lother Walter barrel.)
In total, according to my estimates, more than a hundred shots. It seems to be all right, although it works.(To date, about 1000 shots have been fired). Today (on August 12, 2002) about 1,500 shots were fired from the rifle, mainly on cans and bottles, 22 crows, 1 forty, 1 pigeon and 2 seagulls were killed. All at a distance of 20 to 76 meters, the average distance is 50 meters, there was practically no problems, But the valve “flowed”, or rather the gasket. Now we have changed the design of the valve, we made about 10,000 test “shots”, that is, the valve worked like a shot, dismantled, traces of wear are not visible, we believe that the design was successful. They changed the charging fitting, now there is no union nut, but a fill probe is inserted into the hole and air is opened. The pressure itself holds the fitting there, then the pressure is relieved from the hose and the union is loosened free. (Oh, about this I already wrote :-), for today 88 crows, a good rifle, I like, September 5, 2002). All in all, 150 of them were killed, after which it was sold and one more was made, then one more and more …
Eduard


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