GTA
All Springer/NP/PCP Air Gun Discussion General => European/Asian Air Gun Gates => Turkish AirGun Gate => Topic started by: Mossonarock on October 08, 2018, 09:56:23 AM
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I have a .25 cal Dominator 200 from Hatsan and I would like to replace the spring that is in it. My Dominator is one of the closeouts from HastsanUSA. I tried asking Hatsan directly that if the spring can be replaced and all they had to say is that it would void the warranty. Then I never heard back from them. I am definitely under the impression that Hatsan won't hold up their warranty. I asked for an RMA from Hatsan, since the rifle's fps is way under their specifications using all the pellet weights I had from 16 gr up to 30, only to never hear back from them. So forget their warranty that they only stand behind in order to find reason to NOT support their product in my experience anyway. Its clear to me that the Dominator has a lot of potential if that spring can at least be replaced with a stronger and smoother operating one. I haven't decided if I want to go with another spring or replace it with a gas piston. So, I'm trying to learn what I can before I make a decision.
I'm wondering if anyone has replaced spring with a gas piston. If so, I'd like to know what details there are regarding the end plug that holds the piston/spring in the gun and how the piston catches onto the sear. Are there any alterations that are necessary or is it really just plug and play? I've watched through all of Airgunnersedge's videos on youtube and I'm aware that it appear he had replaced the spring with a gas piston but he didn't show much details about the process. Then there's also that Brazilian video on youtube but he speaks Portuguese.
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I've had a .177 springer Dominator carbine for a few years. Shoots good. 800-850fps depending on pellet weight. I don't think a gas ram would make much difference. I'm not a gas ram fan anyway. Just don't like the sound and the feel of the shot cycle.
Consider this. I have a .177 Proxima. It's the only gas ram I have now because it only comes in gas ram. I'm thinking about putting a spring in it. Except for the repeater part and wood stock it's similar to the Dominator. I like it a lot. It's gotten some bad reviews but it looked to me like they were from guys who couldn't figure out how to properly operate it. Muzzle velocity about the same as my Dominator.
I prefer .177 but I just punch paper or kill a few empty cat food cans or wine bottle corks. I think .22 would give you more options in ammo and a heavy .22 will probably do anything a .25 will.
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Please don't get me wrong. I like my .25 cal dominator but I believe that it can offer more with a better spring whether metal or gas.
I'm hoping to get the performance up to at least 650ish fps with a 25gr pellet. If I remember right, its in the upper 400s fps with 25 gr pellet.
The best I could get is about 600 fps with the lightest alloy pellet I could get- 16 gr I think. I'm not at home so I don't have my notes with me.
To be fair, for the sake of comparison. My weihrauch is almost as buzzy and twangy while shooting as my dominator is. I'm also considering an after-market spring for my weihrauch too for the same reasons. I've honestly been a bit underwhelmed by my weihrauch; its in .22.
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What HW model do you have?
Take the spring out and measure the OD, ID, thickness of spring wire and length. Air Rifle Headquarters or Vortec should have something similar.
While you are at it, order a bunch of spare piston seals and breech seals.
I bet you have a bad piston seal. :-\ Use a spring compressor!
let us know what you do...
-Y
Sometimes you get what you pay for, sometimes not. ;)
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I have an HW97kt in .22 cal. I've only had it a couple weeks and I'm still evaluating pellets for accuracy. After getting my HW, I developed an appreciation for my Dominator as it really is a decent rifle. In comparing the two, I'd say that the Dominator is a wee bit more powerful than the HW, although I think the Dominator should be performing better. I've been thinking of writing up a comparison between the two rifles but I don't know where in GTA it would best to post it. Really though, I'd like to see an unbiased comparison between the two be made in a youtube video.
I may start with replacing the spring in the Dominator with another spring. Then continue to ask around about going from spring to gas. That Brazilian youtube video made it clear that it only takes a couple minutes to switch out the spring in the Dominator.
I'll definitely post what I do and whatever details I can.
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I got a spring compressor yesterday and disassembled the gun. The breech seal was shredded. The piston seal looks like it had a couple edges shaved off of it. The spring had some kinks in it. So, I'll be replacing those. I wonder how many years this rifle sat in a warehouse waiting to be sold.
I took measurements of the spring.
Spring length: 11 5/8 inch (295mm) with 41 coils
Spring ID: 1/2 inch (12.6mm)
Spring OD: 3/4 inch (19.10mm)
Wire diameter: 0.126 inch (3.22mm)
The inside of the piston where the spring goes is 0.858inch (21.8mm)
Taking the measurements was difficult since the spring was so bent out of shape.
Those numbers I provided are averages.
I'm waiting on hearing back from Vortex to see which spring they recommend. I haven't sourced a gas piston but it looks like it should be easy to place a gas piston in the rifle. Considering the price of the springs and the ease of disassembling the gun, I may try a couple springs to see what I get the best performance from.
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Have you checked the compression chamber, if it's two piece design, it should have a oring installed to seal the chamber. Mine did not have that oring, fps increased some after installing it.
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I'm pretty sure its a one piece design. I tried messing with it and nothing would budge.
I put in an order to Vortek for 3 springs just to explore the different performance characteristics because why not.
125 Wire spring 780/785OD
128 Wire spring 825OD
135 Wire Spring 825 OD
All of these springs have an OD larger than the OEM spring. However, there should be plenty of room since the ID of the piston is 0.858inch.
I'm hoping that the larger diameters will also reduce the chances of the spring developing kinks.
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Lucky, both of mine were a two piece design and hard to separate.
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Keep in mind that the OD of a spring increases as it's compressed. If you can halt the order, I would, and get what you need from air rifle headquarters. It's a one stop shop for your tune. Spring, seals, moly paste and heavy tar.
Heavy tar is what is used to smooth out the spring, rid it of the twang, and generally make it feel like gas piston. His moly paste is the best on the market, a drop of that here and there is all you need- metal to metal lube so used in trigger, pivot and anywhere there is metal to metal motion.
http://www.airrifleheadquarters.com/page/page/251327.htm (http://www.airrifleheadquarters.com/page/page/251327.htm)
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The Vortek springs are already delivered. I'm still waiting on the seals from HatsanUSA. The USPS has botched up the delivery and trucking the package all over the continent according to the tracking information. Sometimes, slow shipping is NOT the retailers' fault....
The springs fit in the piston with some play. I haven't tried them yet to see if they work since I'm still waiting on the seals. I'm sure that the 125 Wire spring 780/785OD will work just fine since its essentially exactly the same as what came with the rifle. The other two 825OD springs will just have to see.
Messing with these springs is a learning experience for me.
After I get the ideal specs figured out for a spring for my rifle, I'll try ordering a custom one from ARH if that's possible. Vortek didn't send me springs with the coil count I asked for. They say they do that and I asked but they didn't deliver. The springs are inexpensive enough that I'm not really concerned. Sending them back is way too much trouble for me for the cost.
BTW: Rabbitguy, thanks for providing that picture. I've been wondering what people mean by "there's a space where an o-ring goes." since mine apparently doesn't have such a space. Perhaps I'll try posting a pic of my compression chamber.
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A proper fitting spring guide should eliminate the spring canting. ;)
-Y
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The kinks in the OEM spring are only on the portion of the spring that was above the spring guide. The portion of the spring being guided by the spring guide remained straight. That's why I figured there was way more clearance between the OD of the spring and the ID of the piston wall than there really needed to be. Also, that's why I figured it would be ok to go with a larger OD spring and I beleive I was correct about that.
The seals finally came in yesterday and I got my rifle put back together. By that time it was dark, so no chrony testing. I hope to do that today.
However, I put in the 128 Wire spring 825OD since its the mid sized spring of the three I bought and it seems to work just fine. Remember, the 0.825"OD spring is only 0.075" larger than the OEM spring. I shot a few pellets out the window and into the dark. Shot cycle seemed smooth. So I guess there was enough clearance for the wider OD. So, it appears that 0.025" is enough clearance between the spring and the inner wall of the piston. Whew....
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Some people sleeve their pistons to take up that extra room-and to prevent the spring from coming into contact with the piston wall. Aluminum cans or soda bottles are what a lot of people use.
Tell use how she shoots! Of course if the springs have different ID's, then they might each need a different top hat and spring guide.
-Y
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Forgot to mention that some people, Hector Medina included, believe that a larger ID/OD spring lasts longer. This is due to the steel grain structure and the less tight bend. HM and his website is a great resource BTW. ;) https://www.ctcustomairguns.com/hectors-airgun-blog (https://www.ctcustomairguns.com/hectors-airgun-blog)
Keep us posted...
-Y
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You are kinda going about this backwards.
If you are low on power, the first step is to make sure it is sealed...that it has a good breech seal, and a good, properly fitting piston seal.
A replacement spring is chosen by wire diameter, number of coils, and
spring guide diameter. You want a snug to tight fit on the guide. You don't want to select a spring that is as large in diameter as possible. Uncompressed spring length is unimportant, spring vendors do not even list this figure.
One fellow in this thread said his healthy well sealed gun in .177 shoots 800-850ish fps with mid weight pellets, so your gun in .25 should shoot about 500 fps with 25 grain pellets.
650 fps with 25 grain pellets is not a realistic goal.
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jmars: I'm not "doing this backwards". However, you aren't reading my posts very well. Replacing the seals is something I did and I stated that. So, please save your lectures. Besides, its my rifle and I can tinker with it any way I want to with or without your approval. My .25 cal Hatsan Edge pushes 25gr pellets at about 570fps. My Dominator was 450 with the exact same pellet. That's what this tuning is about. I'm just trying to get the performance up to manufacturer's specs since Hatsan didn't want to honor their warranty with me. If I can exceed manufacturer's spec and retain accuracy, even better but that's not my purpose here.
Yogi: I'll tend to to agree that larger OD/ID springs are likely to last longer. I'm glad that this wider spring seems to work fine.
So, I managed to do some testing with the chrony yesterday. The catch is that my before tuning tests were outdoors and the chrony was about 15 or so feet from the muzzle. The after tuning tests were conducted indoors with they chrony at about 8 feet from the muzzle. So, a casual observation will lead one to believe that the improvements are more than they really are.
I did get to shoot the Predators a few times outside before it got too dark. I'd say that fps difference between inside and outside testing distance led to a 20fps difference in the avg fps measured. These are the after tuning chrony results:
Predator GTO 16.54gr avg fps: 641 <-outside
Predator GTO 16.54gr avg fps: 668 <- inside
H&N Barracuda Green 19.91gr avg fps: 585
H&N Excite Coppa Spitzkugel 24.54gr avg fps: 531
Air Arms Diabolo Field 25.4 gr avg fps: 550
Prior to the tuning, the follow is the chrony results I got:
Predator GTO 16.54gr avg fps: 608
H&N Barracuda Green 19.91gr avg fps: 549
H&N Excite Coppa Spitzkugel 24.54 gravg fps: 486
Air Arms Diabolo Field 25.4gr avg fps: 447
So, I might have gotten an improvement of about 20-30fps. I attribute the improvement to replacing the seals. I don't think that the spring I put in was significantly more powerful. Even though it is made from a thicker wire, it only has 35 coils. The OEM spring had 41 coils. So, I think it evened out. In fact, with the OEM spring I had to use two hands to cock the rifle. With the 128 Wire spring 825OD that I put in, I could cock the rifle with one hand on the cocking lever. So, easier cocking and slightly more fps. I'd say that much of the tune has been a success. Next will be to try the 135dia wire spring.
However, the Air Arms pellet showed a huge improvement and honestly I'm scratching my head over that one.
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I chrony tested the 135 Wire Spring 825 OD last weekend. This spring was significantly stronger than the 128. I could cock the rifle with one hand but two hands was easy, which is sort of how the OEM spring was. The rifle was louder and the pellet obviously hit the target much harder. The sound was almost too much for my ears. I don't think I'd want to go with a stronger spring. So, I'll consider this one to be an upper limit for my rifle.
Predator GTO 16.54gr avg fps: 696
H&N Barracuda Green 19.91gr avg fps: 632
Excite Coppa-Spitzkugel 25.54gr avg fps: 542
Air Arms Diabolo Field 25.4gr avg fps: 523
H&N Barracuda 30.86gr avg fps: 484
When comparing these numbers to the 128 spring, it looks like a mixed bag of tricks. Whereas the Predator pellets showed an increase in fps, the Air Arms appeared to have been slower. A new pellet I tried with this spring is the 30.86gr Barracudas. They were a new tin that I hadn't even opened before. I wanted to see how fast this rifle could push a 30gr pellet. Considering the chrony numbers I'm getting with all these springs, I'm thinking that Hatsan may have used a 20 gr pellet for their testing from which they obtained their advertised fps numbers. So, I think that will be the weight of pellet I'll try to focus on with this rifle.
I put a scope on the rifle to begin sighting it in. However, its too soon to speak conclusively if I can get acceptable accuracy with this spring. I have too many other things to also work out- like setting up a stable bench to shoot from... I suspect though that I'm going to have a hard time getting accuracy with the 135 spring. It took me awhile before I could shoot accurately in the first place with the OEM spring. For now, my opinion is that the 128 spring is about as close to ideal as I can get for this rifle.
If I try any more springs in this rifle, I'd try the 125 and 128 with 40 coils.
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I've continued to use the 135 wire spring and it seems to be loosening up a bit. Now, I'm able to cock it with only one hand on the cocking lever. I'm also hitting my plinking targets and spinners 100% of the time at 25-30 yards. I think I'll leave this spring in for awhile longer, maybe shoot a tin of pellets or so, then chrony test it again. By then, I ought to have a handle on accuracy for what its worth.
I tried contacting Air Rifle Headquarters about having a spring made and they said they won't custom make one-off springs. However, Vortek has a 128 wire spring with 40 coils and I'm not sure how I missed that. I may consider trying that one too.
I hope this experience is useful to other people than just me. I've just been wanting to share my experiences with tinkering with the Dominator since there isn't much I could find on the net.
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I chrony tested the 0.135 spring again and indeed something changed. It looks like avg fps dropped by about 20-30 fps after shooting a tin of pellets.
Predator GTO avg fps: 657
Barracuda Green avg fps: 613
Coppa Spitzkugel avg fps: 504
AA Diabolo Field avg fps: 508
H&N Barracuda 30.86gr avg fps: 468
The accuracy of the 0.135 spring was fine for plinking out to 75 yards. I don't have space to shoot further. However, its not going to win FT competitions in my hands anyway. Not that I care about winning FT comps but you know what mean.
So, switched out the springs and put the 0.128 back in. Immediately I felt the difference. Smoother shot cycle. Pellet on pellet accuracy at 10yards. This afternoon, I'll get outside and try accuracy at longer ranges. Already though, its way easier to hit my plinking targets out the window. The sound of the shot cycle is a pleasant thump with barely noticeable twang but I do have a DonnyFl suppressor on it. When I switched out the springs, I also installed a Vortek tophat and a metal spacer for the spring. This rifle didn't have those items. I'm sure it increased the pre-load on the spring. Dunno if that would help any. I'm still a learner.
Here's chrony results for the 0.128 spring with the new bits:
Predator GTO avg fps: 676
Barracuda Green avg fps: 613
Coppa Spitzkugel avg fps: 535
AA Diabolo Field avg fps: 511
Barracuda 30.86gr avg fps: 472
I find it interesting that there's generally an increase in fps with the 0.128 spring. However, there's the exception of the Barracuda Greens and the AA Diabolo Fields. I can tell when I'm shooting those two pellets that this rifle doesn't particularly like them. They are also my less accurate pellets. I'm kinda disappointed a bit that the Barracuda Greens are less accurate because they are a 20gr pellet. 20gr pellets are what I want to focus on using for this rifle since I still believe that's the ideal pellet weight for this rifle. On the other hand, I tend to get great accuracy with the Predator GTOs which are 16.54gr. The 30gr Barracudas are just too heavy for this rifle. I don't recommend pellets any heavier than 25gr for the Dominator.
If anyone knows of any aftermarket piston seals and breech seals for the Dominator, I'd be happy to take a peak. I'll admit the OEM seal was a bit worrisome with a thin, feathered edge to it from the extrusion process. I didn't bother trying to shave it down.
Also, if anyone knows of a pellet seater for underlevers, I'd like to take a look at that too. The barrel breech is a bit wide and I'm sure I'm probably losing a bit of fps from that.
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Mossonarock, Great write-up of your testing and progress on the Dominator. I will be most interested to read more as you continue testing new springs and other options. My .25 cal Dominator has felt a bit less than, and after reading your posts I have a direction to improve the beast. Thanks!
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Nice. I'm glad my experiences could help. I'm pretty sure that the 0.128 spring is ideal for this rifle for power and accuracy. However, whether the spring ought to be 35 coils or 40, I'm not sure about. That would be the next step to explore. If a person was more concerned about accuracy and didn't care about power, the 0.125 spring may be best but I didn't bother with installing my 0.125 spring. I think I'm going to leave the 0.128 spring in for awhile- a tin of pellets or so like I did with the 0.135 spring.
I got out and did some proper target shooting yesterday. I have to admit that I'm not able to be any more accurate with my HW97 than with my Dominator. That says more about me as a shooter than the rifles. I don't feel that I can speak on accuracy. The groups I get with both rifles are about the same and I won't be winning any competitions with my shooting skills. Laugh if you will, its ok.
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I ordered replacement parts for my Dominator last night; Vortek spring 0.128 with 38 coils, Hatsan breech seals and piston seals. Wanted to try the Vortek molly piston seals but not currently available. We shall see if Vortek sends out a 38 coil spring or the standard 40 that I might need to cut down. Thanks again for making your testing and progress available to the rest of us.
Anyway, trigger time and concentration on your shooting style should help improve the groupings - if that's what you are after. There are a couple of YouTube sites I follow picking up tricks and tips for my shooting every episode. I especially like VarmitHuntersTV because of how well the guys can shoot: be aware it is a hunting site.
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My main challenge is its almost always raining when I get home from work and now with the time change I basically have no daylight either when I get home to do any target shooting. If you are able to chrony test your rifle with the new spring, I'd like to see the results. 38 coils is interesting.
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Firstly: nice work! A lot of guys end up cutting-down their Hatsan springs to make the gun shoot smoother/have less of a harsh shot-cycle, and obviously give up some power to do it. That you have found a spring that shoots smoothly AND makes acceptable power is no small feat.
Aftermarket seals: just my experience, but every aftermarket seal I've tried has disappointed. Many need to be sized, and missing that mystical, magical mark by 1/2 millimeter makes your expensive seal...well...junk. All the seals I have tested aside from one needed sizing to deliver optimum velocity, and none of them delivered the velocity I get from just slapping a new factory seal in the gun. Admittedly I may just be missing the "magic," but I'd rather spend 5 bucks on a seal I know works without the hassle than to spend 10 or more dollars on an aftermarket seal, knowing I will likely ruin at least one or two getting that seal anywhere near its peak. Are aftermarket seals "nicer" than what Hatsan sends? Heck yeah! They're all softer, thicker, make for a quieter and smoother shot cycle, and are turned on a lathe vs. pushed out of a mold (meaning: round, not square like at least 1 out of 3 stock units). They just don't make great velocity.
Pellets: I know it seems counter intuitive, but try a few heavier pellets. My Mod 95 in .25 shoots most pellets well enough, but LOVES JSB King 25.39s. Last time I tested it (with a good stock seal, hone, lube tune, and after buttoning the piston) it averaged 608 fps with these JSBs (at almost 21 ft lbs!), and will shoot them more accurately than I am capable of.
Gas piston: I like a gas piston, even prefer them as I like to airgun hunt, and can leave them cocked while hunting without triggering my OCD. That said, if you look around I think you will find that if you want the most power, you get it from a steel spring. Gas pistons are quieter and feel smoother (to me, anyway), but they typically give-up a little velocity to do it. That said, with no spring tar necessary, they may not lose the velocity a spring powered gun can in cold weather (I've never noticed a difference myself, but I don't live where it gets much below 20 degrees F, and if it does I'm not out in it).
Keep up the good work, I'll be following this post.
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Thank you for sharing your experience. I couldn't find any after market piston seals that I was certain I could use on my Dominator. HatsanUSA reduced the price on their Vortex Dominators and I have to admit that I bought one of those too. It'll be interesting to compare that to the 200S that I have.
I still haven't been able to do any rigorous target shooting but I was able to do some plinking out to 75+ yards today. My accuracy is about the same as with shooting my HW97kt- not great but enough to have fun. Also, the recoil feels about the same. Both rifles buck and kick just about the same. However, I realize that's a very subjective observation. Overall though, I do feel like this 0.128" 35 coil spring is satisfactory. Sometime, I really ought to try the 0.125 spring since I bought it and all.
I didn't dive into this being a complete newb. I had some experience with making my own springs for some antique camp stoves that I have and restored. Some of the European members here may know the stoves I'm talking about- Radius, Primus, Optimus. So, I had some understanding of wire diameter, coil count, spring OD and how all that works together. However, making a spring for an airgun is totally out of my league. That's why I didn't choose to cut down the OEM spring. Besides, I prefer leaving original stuff as original as possible. Swapping out parts is ok but I don't like permanent alterations.
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HatsanUSA put up the Vortex Dominators for close-out sale. I couldn't resist and bought one. Now I can really compare spring vs gas.
I haven't had time to do much chrony testing for the vortex dominator. I took it apart and cleaned it up. Initial fps for Barracuda Greens 19.91gr after cleaning seems to have settled around 700fps. That's almost 90 fps faster than the 0.128 spring. I'm curious to see what speeds I'll get with the other pellets.
I found significant differences in build quality between the two rifles with the spring dominator having better fitted components. The components on the vortex dominator just don't seem to fit together quite as well. I had a really hard time pulling the trigger out and putting it back in. So, its interesting that I'm a getting faster speed with the vortex dominator. I haven't figured it out.
Back to my original question for this thread: can a gas piston be put into the spring dominator? I believe the answer is yes. However, the end plugs for the two rifles is very different. I'll try to put up pictures sometime. So, if someone would want to swap powerplants, they'd also have to swap end plugs. Otherwise, without taking careful measurements which I did not do, a casual observation indicates everything else looks the same.
Well, the clients are pouring in here at work. So, that'll be all for now. This evening I need to split firewood. Not sure when I'll get to that chrony testing.
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Chrony testing with the vortex dominator:
Predator GTO avg fps: 786
Barracuda Green avg fps: 697
Coppa spitzkugel avg fps: 601
AA Diabolo Field avg fps: 561
Barracuda avg fps: 524
Summary: anywhere from 50 to 100 fps faster than the .0128 spring.
I wonder it there's differences in how the rifles are built and engineered. Or if its merely a powerplant difference. I'll have to swap powerplants to see, meaning take the spring out of the Dominator 200S and put it in the Vortex Dominator and vice-versa. Mysteries.
One thing I found interesting is that the extreme spread and standard deviation for the pellets was similar with both rifles even though the avg fps was very different. I'm going to attribute it to the pellets. Meaning some had more irregular shapes and some were more uniform and all that stuff. The Barracuda Greens and Coppa Spitzkugels tended to have wider standard deviations while the Predator GTOs had the tightest standard deviation and extreme spread.
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'Airgunners Edge' on youtube converted a Hatsan 200s from spring to gas ram. I believe he was able to obtain the necessary parts for the conversion directly from Hatsan, but not sure.
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I finally got a round tuit and tried swaping powerplants between the two dominators. The end caps for the two rifles are different and each endcap had to go with its respective power plant. The spring went right into the vortex dominator and worked right away. However, when I put the vortex piston and its end cap went into the spring dominator, the seer wouldn't engage. Later on, when I put the spring back into the spring dominator, the seer still wouldn't engage. After taking the rifle apart and putting back together several times, the seer finally would engage again. By that time, I was sick of it and didn't want to bother putting the vortex piston in it. I did some chrony testing with the 0.128 spring in the vortex dominator and here are the results:
Predator GTO 16.54gr avg fps: 777
Barracuda Green 19.91gr avg fps: 693
H&N Field Target Trophy 20.06gr avg fps: 658
JSB Exact King Diabolo 25.39gr avg fps: 595
Barracuda 30.86gr avg fps: 511
Since I ran out of some of the pellets I had been using, here's a baseline chrony test with the vortex piston in the vortex dominator:
Predator GTO avg fps: 779
Barracuda Green avg fps: 702
H&N Field Target Trophy avg fps: 639
JSB Exact King Diabolo avg fps: 586
Barracuda: 496
Looks like the 0.128 spring delivers very close to the same power as the stock vortex piston in the dominator. I found that very interesting. As I mentioned awhile ago, I had also gotten a 0.125 spring and hadn't yet tried it in the spring dominator. I finally did after I got that seer to engage. (not sure what I did to get it working again) Here's chrony results with the 0.125 spring:
Predator GTO avg fps: 698
Barracuda Green avg fps: 626
H&N Field Target Trophy avg fps: 589
JSB Exact King Diabolo avg fps: 526
Barracuda avg fps: 479
I'm still trying to make sense of these results. At first glance, it appearsthe 0.125 spring is able to deliver similar power to the heavier pellets. There could be some issues of difference since the top hat wouldn't fit the 0.125 spring. So, I couldn't use it. The spring may not have been lubed enough. And who knows what else? Also, I shot some of those JSB pellets at a rat-on-the-run field target using the 0.125 spring and collected some of the splattered pellets for a photo. It looks like the 0.125 spring is able to deliver enough power to a pellet to fully flatten it upon impact at 30 yards. Below that is a pic of the two actions of the dominators side by side.
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If you don't already have a Hatsan fill probe and a HPA hand pump, I suggest you consider buying both now. You can use them immediately to vary the pressure on Vortex pistons to simulate MANY different power levels. You will also want to have the pump on hand later for your first PCP acquisition. If your future PCP stores less than 400cc the hand pump should be all you need.
Links below are the ones I ordered off ebay. Both are working well to fill my Bullboss and Vortex air springs. Not endorsing these sellers, just using the listings as examples.
Note: Overseas shipping time was not bad for my order, but sometimes it can be really SLOW!.
https://www.ebay.com/itm/PCP-Airgun-Hand-Pump-High-Pressure-Hand-Pump-for-Benjamin-Hatsan-HPA-4500psi/401314270659 (https://www.ebay.com/itm/PCP-Airgun-Hand-Pump-High-Pressure-Hand-Pump-for-Benjamin-Hatsan-HPA-4500psi/401314270659)
https://www.ebay.com/itm/FX-Fxgun-Webley-Hatsan-RWS-Prestige-Evanix-PCP-charging-filling-Probe/123143967568 (https://www.ebay.com/itm/FX-Fxgun-Webley-Hatsan-RWS-Prestige-Evanix-PCP-charging-filling-Probe/123143967568)
From your photo it looks like the main tube has the holes drilled in it to access the Vortex bleed screw and the fill port while still in the action. That makes "tuning" go a lot faster since you don't have to pull out the spring for each adjustment. I don't know what your Vortex pressure should be for that rifle, but I'd check the max spec written on the Vortex spring so you don't exceed that value.
Similar to your coil spring testing, I'd change the air spring pressure and test many different pellets for velocity, consistency, and accuracy. Unless you can find some factory recommendations, I suggest starting at 100 bar and going up in 5 or 10 bar increments, but never exceeding the ratings on your air spring. I think you will be able to find a "sweet spot" pressure that will give you a nice smooth shot cycle with good accuracy near the velocity/energy you want.
I had a weak Vortex (~60 bar?) in a used Mod95 that I pumped back up to 150 bar. My Vortex said "160 bar max" on the side label so I thought 150 bar was good pressure. The rifle returned to shooting at factory velocity, but the shot cycle was a HUGE WHUMP! and I almost needed 2 hands to cock the darn thing! I later read that the suggested pressure for the Mod95 Vortex was 120bar to 130bar. I popped the stock, opened/closed the bleed screw, and re-pumped the Vortex back to 125 bar. Rifle STILL shoots at factory velocity but is easier to cock and now has a "short thump" shot cycle. That was a nice "proof" to me that beyond an optimum value excess spring energy does NOT transfer to the pellet. That extra energy just goes into thrashing the gun (and the shooter) a lot harder than is necessary.
Good Luck!
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Mikeyb,
I appreciate your enthusiasm. Please share chrony data with your rifle. I'm pretty much done with any testing now. I'm still waiting for a day with good weather when I have time to shoot to work on my marksmanship. I really liked the results I got from the 0.128 spring but I still have the 0.125 spring in it. Also, as I said, I think pellet weights between 20 and 25 gr are ideal for this rifle in .25 cal. I'd love to hear other's opinion and experiences with this subject.
If I made any adjustments to the vortex piston, I'd reduce the gas pressure. I wouldn't increase the pressure. I have a hard time shooting that rifle accurately. I think the OEM stock pressure is more than enough for this rifle.
This is totally outside of anything I'm will to do but I wonder about tweaking the dimensions of the transfer port- such as rounding out the edges maybe making it a wee bit wider. But I won't be attempting anything like that.
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Mikeyb,
I appreciate your enthusiasm. Please share chrony data with your rifle. I'm pretty much done with any testing now. I'm still waiting for a day with good weather when I have time to shoot to work on my marksmanship. I really liked the results I got from the 0.128 spring but I still have the 0.125 spring in it. Also, as I said, I think pellet weights between 20 and 25 gr are ideal for this rifle in .25 cal. I'd love to hear other's opinion and experiences with this subject.
If I made any adjustments to the vortex piston, I'd reduce the gas pressure. I wouldn't increase the pressure. I have a hard time shooting that rifle accurately. I think the OEM stock pressure is more than enough for this rifle.
This is totally outside of anything I'm will to do but I wonder about tweaking the dimensions of the transfer port- such as rounding out the edges maybe making it a wee bit wider. But I won't be attempting anything like that.
I've read a lot about modifying transfer port size. IMO there are RARE instances for very specific rifles where this advanced mod can improve rifle performance. Most air rifles we are likely to acquire already have optimum transfer port sizing and any mods in this area will probably cause a performance drop. Just advising caution.
I think there may be a place for a Dominator in my collection. Really like the look of that series and I don't have any sliding compression tube style under-lever models yet. I initially though the sliding barrel mechanics of the Torpedo series was "crazy". After getting a cheap Torpedo refurb, I am now a big FAN of that series. Awesome power and accuracy, but HEAVY!
The images below contain my chrony data for the Mod95VQE22 which I repaired/adjusted. We are in complete agreement that factory Vortex pressure is near optimum for each specific rifle. Tuning pressure up is a usually a bad idea, but tuning pressure down "may" give you a smoother more accurate rifle.
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Unfortunately what I have found along with others is the dominator has an Engineering flaw with the breach seal compartment, does not seem to be every gun but a lot , I have done almost everything possible except machine the tubing for a seal to sit on the nut of the barrel for a better seal... think I made a out 8 YouTube videos of this gun... My problem is I love looks and accuracy of this gun when it is functioning properly...
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Richard, I've seen a lot of your videos. At first, I thought my dominator might be one with a breach seal issue. After messing around with it, I don't think that is the case. However, its obvious Hatsan did several manufacturing runs of these rifles and some engineering specs were changed with each run. Although, I think the variability is only true with the coil spring models. I think they got production standardized without the bugs for the vortex models. And my research seems to support that since there's a lot of difference in fps between the spring and vortex models with using the 0.128 spring. I wish I could have gotten the spring dominator to work with the vortex piston in it. If anyone has any other interpretations of the data I've presented here, I'd like to hear it.
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A possible explanation... maybe?
Gas springs have a very limited dimensional operating range. Not enough preload and a gas spring will tear itself apart. Too much preload and it will bottom out before piston latch. Coil springs will eventually bottom out or become "coil bound" if compressed too far, but they will usually function over a much larger range of manufacturing tolerances and user adjustment.
I did a little experiment last year replacing an Edge spring with a Crosman Nitro piston. I'd researched similar conversions and after taking careful measurements found I needed a custom bushing to center and space the NP body correctly in the edge. Turned a piece of scrap nylon in my "wood" lathe to get a perfect fit for the base (cylinder) end of the NP.
The other (shaft) end of the NP needed to be centered in a shallow dimple at the back of the piston head. This dimple is either cut into the piston metal itself or can be a separate metal disk with a centered depression for the NP shaft. I had tuned an older Edge and the back of that piston head did NOT have the centering dimple. To my surprise the one I decided to experiment on DID have the dimple already cut into the piston! I think Hatsan made a design change so coil or Vortex springs could use the same piston with no extra centering disk needed.
The point to this long story is that both the rear bushing dimensions AND the piston dimensions need to be precisely correct for a coil spring rifle to function properly with a gas spring installed. You swapped (coil spring + guide + tophat) and (Vortex + spacer) which is correct. But if there is ANY difference in the piston dimensions, you may have needed to swap pistons also.
If your spring version piston has no dimple, then the Vortex spring MAY have had too much preload and bottomed out BEFORE the trigger could latch the piston.
The coil spring + guide+ tophat should work fine in either rifle since a dimpled piston would not affect the springs operational length.
If you ever take apart the rifles again, look for a centering dimple at the back of the piston heads. I think your Vortex rifle piston has one and the spring rifle piston does not.
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I was also wondering about the gas piston possibly bottoming out and thereby keeping the seer from engaging. But then I had the same problem with the seer not engaging when I put the spring back in. Then the problem went away on its own or so it seems. So I dunno.
The two cylinders do differ in the that the vortex has that dimple you mentioned and the coil springer doesn't have one. I would suspect that's the reason for the seer not engaging but it didn't want to engage for a few times with the spring in it either. ??? :-\
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I finally found a pellet that produces ragged hole groups at 25 yards- JSB Exact King 25.39gr!!
That's with the spring Dominator. I still don't know which pellet works best in my vortex Dominator.
Yay!!
I haven't had a chance to try longer distances yet since.... I'm out of ammo.... And waiting for the brown santa...
I'm still dealing with flyers but at least I know my scope isn't broken and every other thing on that list of what may be affecting accuracy.
Whew.
Really, having the right pellet is the difference between targets that look like they've been shot by a shotgun vs looking like someone was actually aiming at a spot and hitting it. The stories are true. I wasn't really even looking. I put the .128 spring back in the rifle for the last time and was just running pellets through it to get the rifle settled in and these JSBs actually shot a 1 inch group at 25 yards without me really even trying. I was surprised.