Setting the regulator & hammer spring tension correctly

Forums PCP Airguns Setting the regulator & hammer spring tension correctly

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    Setting up the regulator & hammer spring tension correctly is a simple but tedious process, but done correctly yields great results. Something to remember is that you want your regulator set at the lowest possible pressure that will achieve the velocity you seek, so as to give you the most shots and the least wear and tear on your rifle…you don’t want to run your gun at the ragged edge of its performance capability.

    For example, let’s say you want to shoot 34 grain pellets at 800 ft/s… which yields 48 ft/lbs energy at the muzzle. Let’s say you start out by setting your regulator at 120 Bar…then the next step is to set your hammer spring tension. My advice is to back the hammer spring retaining nut all the way out, and then screw it back in until it just catches the first threads, then make a reference mark at the top of it at the 12:00 position. Then screw it in using the mark to count your turns to say 6 turns in…then shoot a few shots over your chrony to see what the pellets velocity is. Then turn it in a half turn so it is at 6 1/2 turns in and shoot a few shots over the chony…then to 7 turns in…then to 7 1/2 turns in…etc. As you turn the hammer spring adjustment nut in and shoot over the chrony you will see the velocity increase. You will keep turning it in until you get to the point where the velocity begins to fall back lower,  and that is when you back it off until you find the “peak” setting where even 1/4 turn in more will cause it to decrease. This then is the optimum hammer spring tension for that particular regulator setting.

    So now let us say you did all of the above and your peak velocity turned out to be 750 ft/s, which is lower than you wanted. So then you would set your reg pressure up to 130 Bar and repeat the hammer spring tension adjustment procedure until once again you reach the peak of adjustment and determine if the velocity is where you want it to be. Setting the regulator pressure up 10 Bar results in about a 30 ft/s increase in the pellet velocity, providing you adjust the hammer spring tension to its peak setting.

    To confirm the regulator setting, simply fill the air tank on your gun up to say 150 Bar and shoot pellets over the chrony until it eventually falls below the reg pressure as shown on the rifle’s air gauge. You will know when this happens because lets say all your pellets are shooting close to 800 ft/s and all of a sudden a shot will show on the chrony at 780 ft/s…and the next one will show at 745 ft/s for example. If you have your regulator pressure set too high and the hammer spring tension set incorrectly, you will actually see your pellets velocity go up higher when it falls below the regulated pressure as shown on the air gauge, instead of the velocity going lower.

    As I said before, it isn’t very complicated but it is somewhat tedious. For those of us who appreciate the best accuracy and performance from our rifles this is a labor of love and is a pleasure to do. I do caution you not to rely too much on what others may say the “best” regulator setting is for a particular pellet from a certain rifle…because you will find a great disparity of settings from one gun to another. One gun may have a real high reg pressure setting with the hammer spring nut adjusted only 5 turns in, while another gun has the regulator properly set lower but with the hammer spring nut adjusted 8 turns in. 

    An example of the disparity in settings would be my Streamline .25 that has a Huma reg in it set at 120 Bar, and shoots the 34 gr. pellets at 825 ft/s average…whereas my Wildcat .25 has the same type of Huma reg in it set to 140 Bar, and shoots the 34 gr. pellets at an average of 800 ft/s. Both rifles have the hammer spring tension set at the perfect peak of adjustment and yet there is a 20 Bar difference in their regulator settings. Is there a difference in the regs? Is there a difference in the pressure gauges from one rifle to the other? I surely don’t know! What I do know is that my Streamline originally got about 30 shots and now gets 51…and my Wildcat originally got 40 shots and now gets 64. And the best news is that I no longer have regulators that creep up & down every time I turn around, and I get an extreme spread of around 6 ft/s now. 

    To me this is the foundation for accuracy to which I add cleaning my pellets with Acetone and lubing them with Napier Pellet Lube, and using a Huggett suppressor which also acts as an air stripper, and drilling small holes in my shroud tubes to vent the blast of air diverted backwards, and set my triggers to about 4 ounces, etc. This is how I get 5 shots exactly in the first hole at 50 yards. I hope any of this helps someone out there who may be struggling to understand how to set up their rifle. And for heaven’s sake if you have an unregulated rifle find a way to regulate it.

    As a footnote I want to make one last comment regarding accuracy, and that’s the fact that even though I can put 4-5 shots in a row into exactly the same hole at 50 yards with either one of my FX rifles I have several friends who cannot. The best one of my friends can do is 1″ to 2″ groups, and my other two shooting friends can’t do any better than 1″ groups with my rifles. My point is that regardless of how well the rifle will shoot, you still need to learn the right way to use the trigger, and how to control your breathing, etc. And above all you have to practice…A LOT! And as you practice a lot you will have moments of sheer joy when you realize you just figured out some new little trick to shooting better.
    This is what makes shooting FUN for me. 🙂

    Best regards, Chuck

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    I received a message from someone who had trouble understanding my explanation of how to set the regulator pressure and hammer spring tension on pcp rifles, so here is the explanation on how to do this from Huma. Hope this explanation answers any questions that mine did not…
    Best regards, Chuck

    How do I adjust my rifle properly:
    There is unfortunately not one general answer to this questions, but we will try to help you out with some advice to understand the principle of a regulator and the settings. Please note, all information in this sheet is general, and just an indication and may vary per model and type of rifle.

    The basic step:
    Start to adjust your rifle so it shoots with a constant pellet speed. After the rifle is shoots constant, start working on the preferred pellet speed; changing one setting at the time Respect the common regulator pressure setting: These settings are based on average FAC rifles. .177 in 8,4 gn. is around 125 bar. .22 in 16 gn. is around 130-135 bar. .25 in 25 gn is 140-145 bar. (BSA rifles tent to be a bit higher) These pressures should bring you close to the average pellet speeds of about 270- 285 m/s. Adjustments can be possible but only if you know what you are doing. Short barrels need more pressure to speed up the pellet compared to longer barrels. Heavier pellets also need more pressure to achieve the same speed as lighter pellets.

    Airflow:
    Your rifle’s power is determined by a mix of components like hammer weight, hammer spring tension, regulator pressure and diameters of transfer ports and or other air restrictions. Most rifles use a sort of “self regulating behavior” of the valve. This is based on certain transfer port diameters combined with valve diameters. When using a regulator you do not need this “self regulating behavior” anymore and you will get the best results when you optimize the airflow. Remove restrictions (as far as they are used in your rifle) and check transfer port sizes. (Normally FAC rifles already have proper diameter transfer ports)

    How to adjust my hammer spring tension in combination with the right regulator output pressure:
    When you have fitted your regulator start using the lowest hammer spring tension and start shooting and measuring with a chrony. Shoot slowly like on the range. After every shot turn up the hammer spring tension a bit. You will see a small adjustment of hammer spring tension will give a relatively higher pellet speed. At a certain point you will notice although you can adjust the hammer spring tension even more, the pellet speed won’t get higher or even gets lower. This means you have reached the maximum pellet speed in this pressure setting. If you would like a higher pellet speed, please adjust the regulator pressure some higher, following the instructions here. 10 bar increasement will approximately give 10 m/s more pellet speed. Too much hammer spring tension with too low regulator pressure will resolve in high air consumption.

    When you followed the steps above and you notice you can get a pellet speed much higher as preferred, you should also decrease the regulator output pressure. If you continue with a too high regulator pressure, and you adjust the pellet speed only with your hammer spring tension, there is a possibility your pellet speed will climb when pressure gets below the regulator set pressure. Hammer weight: An unregulated PCP rifle needs a relative heavy hammer to open up the air valve in the full pressure range (200-100 bar) When a regulator is fitted you will have a constant “lower” pressure on your air valve. This means the hammer can open the valve easier and often does not need as much power and weight compared to an unregulated rifle. Sometimes losing some hammer weight can have a positive effect on the air consumption. Please don’t start drilling and grinding on your hammer directly, but check the several airgun forums. You will find a lot of information on your specific rifle and tuning it to even higher performance. Whenever I find usefull video’s on the web I will post the links in the fitting instruction.

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    mubhaur
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    True and perfect explanation.

    regards,

    Umair Bhaur 

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    sirk
    Spectator
    Spectator

    it must have costed you considerable time to figure this out.

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    Crusher
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    Very good explanation. Thanks for taking the time to share this with us.

    Crusher
     

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    Saltlake58
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    Thank you for that long tedious post.  The information is excellent.  My next gun will be regulated (3/4 of the way there!) and this information will be incredibly valuable.  Information like this is why I cruise the forums.  learning from someone else’s experience!

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    Thanks for the kind words you guys…and Saltlake58 let me say that this information cost me a lot of time and money and heartache – not to mention the fact that my old hands are full of arthritis which makes it very painful for me to type at all, let alone that long tedious explanation.  But like you I have learned so many wonderful and incredibly valuable things related to this sport from right here at AirgunNation. This forum is just the best because of the quality people who come here and Michael’s guidance, which demands the best of us all. God bless him for providing this forum for us…it must cost him a lot in time and energy to do so.
    All the best, Chuck

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    SocalTrail
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    Thanks much, wonderful information here!!

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    Greisdor
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    Hi Chuck.  Once you set everything did your velocity spreed get in single digits over 10 to 25 shots?

    JR

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    Yes, but don’t be misled by achieving a very low extreme spread. An example would be the Kral air rifles…I have seen videos of guys shooting  the Kral air rifles over a chronograph and it shows a very low extreme spread, and yet the rifles shot really poor groups at 50 yards. I don’t know if there is a problem with the barrels or what, but I do know that you can have a very low extreme spread and still not be accurate at the target at longer ranges. Hope my answer helps any…
    Chuck

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    Dartagnan
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    Most Excellent explanation Chuck! 👍🏼

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    Thanks D’artagnan!  🙂  I am smiling  because I’m thinking that just a few years ago I came to these forums in total ignorance looking for answers to a million questions…I am amazed at how much I have learned from all you guys, and that once in awhile I am the one answering a question instead of asking one! 
    All the best, Chuck

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    Paio
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    Thank you Chuck for the very detailed and well explained adjustment process. Since I read your post I have been dreaming about regulators, hammer spring and pellets. It is like an obsession! 

    Anyway, I am ordering a Huma regulator for my Wildcat .22. I am looking forward to reduce my current spread of 15FPS and enjoy a more accurate gun.

    Thanks again for your post.

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    Hello Paio,
    Please define what you mean by saying you want to “enjoy a more accurate gun”. Do you seek 1/4″ groups or 1/2″ groups, and at what range? More accurate at 25 yards, or 50 yards, or 75 yards? Are you getting an excessive amount of flyers? Tell me exactly what you mean when you say your Wildcat is not “accurate”.
     
    I would hate for you to replace your regulator in the belief that it will make your rifle more accurate, when it may not be your regulator that is causing the inaccuracy problem. There are many things that could cause your rifle to be inaccurate, and changing your regulator may not solve the problem. An extreme spread of 15 ft/s is not that bad – as long as it is not fluctuating wildly higher or lower –  so I have to wonder if possibly there may be something else causing your rifle’s poor accuracy. There are many things I would check first before replacing your regulator…here are a few:

    Check to make sure the scope ring caps are tight – Make sure the scope mounts are tightly secured to the scope rail – Try your scope on a different rifle to make sure it is holding zero, or try a different scope altogether on your rifle – Make sure the ocular is adjusted correctly so you see the reticle perfectly – Make sure your pellets are not clipping the moderator on the way out – Try different kinds of pellets to see which one your barrel likes the best (JSB 16gr or 18gr should do well) – Make sure you clean the barrel thoroughly to remove the gunk the factory puts in to prevent rust from developing in shipping – Try cleaning your pellets and lubing them with Napier Pellet Lube – Make sure the stock screws are tight – Make sure you use something like a Tipton Gun Vise for accuracy testing so the rifle is not moving – Make sure your trigger is set light enough so that you are not pulling your shots off target – It could be something as simple as which part of your fingertip you place on the trigger…for example if you place the trigger in the first crease of your fingertip it will cause you to pull your shots to the right. 

    Please understand that the regulator’s relation to accuracy is simply to give consistent results – the same amount of air for each and every shot. If it is working correctly it will not fluctuate more than a few feet per second from one shot to another. The reason I replaced the regulators in my rifles is because after much use they began fluctuating wildly up and down, which gave me real crazy groups on target. That erratic behaviour led me to think that it was my scope that wasn’t holding zero, but through a process of elimination I figured out that it was a faulty regulator and not the scope. So check all of the things I mentioned above before you change your regulator, unless you just love to tinker with your gun like I do in which case I say by all means, change away! 🙂

    All the best, Chuck

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    parallax
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    Hi Paio –
    For your reference, my stock .22 Wildcat has an extreme spread (ES) of 36 fps or 4% variation for 66 shots.  Your 15 fps ES seems pretty good compared to mine.

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    sonny
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    great info Chuck Thanks

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    Paio
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    Chuck:

    Se my answers below your questions/recommendations:

    Do you seek 1/4″ groups or 1/2″ groups, and at what range? 
    A) 1/4″ at 50m (55 yards) and at least one MOA at 100m (110 yards). 25m is damn accurate. One pellet after other same hole. Have done 3/8″ in 50m but not consistent.

    Are you getting an excessive amount of flyers? 
    A) They have diminish considerably since I started sorting, cleaning and re-sizing my pellets. I am due to improve the process and will do a write-up after if my results improve. I use an adjustable pellet sizer from T. R. Robb (http://www.trrobb.com/product/adjustable%20pellet%20sizer%20177) and pelletgage. My pellets all have same head dimensions and skirts diameters. I weight them for long distance shots – 100/150m.

    Tell me exactly what you mean when you say your Wildcat is not “accurate”.
    A) I should say my regulator is not as accurate as yours. If I have less ES I believe my groupings would be smaller.
     
    Check to make sure the scope ring caps are tight
    A) Yes they are. My scope is Hawke Sidewinder 30 Tactical SF 6.5-20×42 – ½ Mil Dot 20X Reticle. All my scopes are new and holding zero.

    Make sure the scope mounts are tightly secured to the scope rail
    A) I have FX adjustable rings. Good quality and always tight. 

    Try your scope on a different rifle to make sure it is holding zero, or try a different scope altogether on your rifle
    A) I ordered a MTC Viper Pro 5-30×50. Let’s see if it changes anything. 

    Make sure the ocular is adjusted correctly so you see the reticle perfectly
    A) All perfect. I am very keen on mount the optical systems the right way.

    Make sure your pellets are not clipping the moderator on the way out
    A) I use FX fixed moderator for .25 caliber in a .22 barrel. No clipping at all. I am thinking to drill some small holes on the back of the moderator as you did to avoid air turbulence.

    Try different kinds of pellets to see which one your barrel likes the best (JSB 16gr or 18gr should do well)
    A) Mine is JSB 18.13 grains. I have tried others but not as good as the 18 grains. I will try the new 25.4 grains when available here.

    Make sure you clean the barrel thoroughly to remove the gunk the factory puts in to prevent rust from developing in shipping
    A) I do it every 300/400 shots or when the POI dramatically changes. I have done so far around 4000 shots with my Wildcat. 

    Try cleaning your pellets and lubing them with Napier Pellet Lube
    A) Yes I clean them all. Unfortunately Napier Pellet Lube is not available here. I am trying different lubes and methods. Planning to do a crazy experiment by mixing 2 stroke synthetic oil and naphta on a 1/35 proportion, submerging the pellets and let them dry (nafta evaporates quickly leaving the lube in a very thin layer). Its supposed to have a microscopic film protecting the pellets as I read in other forum. Will test on Sunday…

    Make sure the stock screws are tight
    A) All good

    Make sure you use something like a Tipton Gun Vise for accuracy testing so the rifle is not moving
    A) Will do soon. 

    Make sure your trigger is set light enough so that you are not pulling your shots off target
    A) That is something I have to pay attention. I use the gun also for hunting and I am always afraid of very light triggers. Will check it. 

    It could be something as simple as which part of your fingertip you place on the trigger…for example if you place the trigger in the first crease of your fingertip it will cause you to pull your shots to the right. 
    A) I have developed a “muscle memory” and always hold the gun in the same position. However, I think I can improve things to keep consistency. Triggerwise/fingertip position is correct. 

    Please understand that the regulator’s relation to accuracy is simply to give consistent results – the same amount of air for each and every shot. 
    A) Yes. This is what I am looking for – same amount of air…

    This is ll of the things I mentioned above before you change your regulator, unless you just love to tinker with your gun like I do in which case I say by all means, change away! 🙂
    A) Part of my hobby is tinker things… Gun, pellets, accessories… I will make sure all the points are well covered before replacing the regulator.

    Thanks mate for your suggestions above. Will do it and I will be back with my results.

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    Paio
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    “parallax”Hi Paio –
    For your reference, my stock .22 Wildcat has an extreme spread (ES) of 36 fps or 4% variation for 66 shots.  Your 15 fps ES seems pretty good compared to mine.

    
Thanks parallax. Your regulator has the same pattern as mine. The initial velocity is lower than the average ones and similar to the last shot. Assuming the regulator is 120BAR I think I have to stop shooting at 130/125BAR so the first shot speed will be higher. I don’t believe FX regulators cycle properly when we refill the gun. It cycles when I shoot. I wonder how the Huma regulator works. 

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    Hey Paio, 
    It looks like you are covering all the bases but I am wondering if your expectations are too high for the Wildcat .22…So can any of you other guys out there with Wildcat .22 rifles please tell Paio what kind of groups to expect with his rifle at 55 yards – and at 75 yards – and at 110 yards? I personally have not heard of honest groups better than about 1″ at 50 yards and 2″ at 75 yards with the Wildcat .22.

    And I will tell you something else about your extreme spread…you say you think that a lower extreme spread will give you the accuracy you seek, but I honestly don’t think so. Because there were times in the past with my FX regulator that my Wildcat .25 had an extreme spread of 30 ft/s and yet it was giving me 3/8″ to 1/2″ groups at 50 yards using the JSB Heavy 34gr. pellets. 

    Paio my brother I think maybe you are comparing apples to oranges when it comes to the kind of accuracy you seek. Because I just don’t believe the JSB 18.13gr. pellets will ever have the ballistic coefficient and buck the wind like the 34 grain pellets do for .25 caliber. Please forgive me for saying so, but to find the accuracy you are seeking at these longer ranges I believe you will have to move up to a Wildcat .25, or possibly an FX Impact .25, or maybe the FX Crown .25.

    From my heart brother Paio, I caution you to not to try to turn something into something it is not capable of being. A few years ago I spent a ton of money trying to turn an inaccurate rifle into an accurate rifle, even had three Lilja Custom Barrels made for it, and three Korean custom barrels with different twist rates also made for it…after it was all said and done I had spent thousands and thousands of dollars on a foolish pursuit. I could have bought five accurate rifles for the money I wasted. I learned a very expensive lesson – if you want an air rifle that is very accurate at long distances…buy one! But don’t waste money and frustrate yourself trying to turn something into something it was not meant to be. 

    All the best, Chuck

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    Paio, 
    I will give you another example…at the range two weeks ago there was a guy shooting at the bench next to me. He had two .22 long rifles – one was bolt action and the other one was semi-auto. He sat there and tried a dozen different kinds of ammo and his very best groups were 3″! When we would go out to check our targets he was just sick at heart comparing his groups to mine. So he said that he thought maybe to take his rifles to a gunsmith to have them “accurized”! I told him not to because once you start down that road you just keep shitting out more and more money.  $$$$$$$$$$$$$$$$$

    I told him the best thing he could do was to sell both of those inaccurate rifles and buy one accurate rifle instead. I told him to buy one of these four: Anschutz XIV Carbine,  Ruger M77/.22, Sako Quad .22, or the CZ 452…with Eley Subsonic ammo any one of those four rifles will do 1″ groups or better at 100 yards. And if he wanted to shoot out to 600 or 1000 yards I would tell him to get a rifle chambered for .308 or 6.5 Creedmoor…but no .22 will shoot accurately at those longer distances. Hope anything I have said helps you make a good decision my friend.

    All the best, Chuck
     

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