Tunining down a springer
Printed From: Kiwi Airgunners
Category: Technical
Forum Name: Pauly's Technical Area
Forum Description: Technical information, Modifications and DIY projects are all in here
URL: www.kiwiairgunners.co.nz/forum_posts.asp?TID=1180
Printed Date: 12 Mar 2025 at 9:14pm
Software Version: Web Wiz Forums 10.14 - http://www.webwizforums.com
Topic: Tunining down a springer
Posted By: Pauly5
Subject: Tunining down a springer
Date Posted: 05 Mar 2025 at 7:47am
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One of my clients in a warehouse has a small sparrow issue and has asked me to recommend a gun. There are often a lot of lower priced guns available, but far too powerful. (I would prefer 177) So this got me thinking how well would such a gun respond to being tuned down to sub 10 ft/lb. My current sparrow gun is an old Air Arms S200, and i'm shooting 7.4 grn pellets at around 7 ft/lb. I know it's a pcp, but it's a really good power. I would cut the spring, but not too much, and put an extention on the piston, effectively reducing the swept volume. Has anyone gone through this exercise, or have opinion on how succesful this could be? It's a pity the cheap air chief guns are so bad. I have one of those still. (It won't fit in my rubbish bin so it stays.
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Replies:
Posted By: tonycee
Date Posted: 05 Mar 2025 at 8:24am
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Hi Pauly, I have a Webley Dominator in .177 Which is made by Hatsan. When I bought it, It had a horrendous twang and violent recoil so I stripped it and shortened the spring by 45mm [ the amount of preload] and added a 45mm spacer between the spring and piston to restore the preload.I also made up a delrin spring guide and top hat and renewed the piston seal and cleaned and lubed it. It now cocks smoothly and shoots with no twang and controlled recoil. I didn't test the fps before the work but is now doing 850 fps with 8.4 g Exacts. I also tried a Hatsan 125 spring in it which is about the same length but lighter wire and less coils. That only produced 700fps with the Exacts. So shortening the spring certainly works and the de-tuning certainly improves the shot cycle and subsequent accuracy. My only problem now is the Webley is too heavy for my tired old arms and will have to go. Cheers. ------------- tonycee |
Posted By: J-S
Date Posted: 05 Mar 2025 at 8:40am
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I bought my tx200 at full power 16fpe, added a tbt short stroke kit which retained the strong spring, with a coil cut off it then shot 10.5fpe, smooth as, and very snappy with the strong spring. If you bought a 18fpe gun like a fusion and added a short stroke tip you would have half inch or so more preload that could allow you to trim the spring.. if you change to a slightly weaker spring you would again drop power so I can imagine you could get down to 8fpe ok. You’d need a gun that you can add custom guides to so it remained firm on the new spring. If you found a good 12fpe gun - hw50 or similar you could choose either weak spring or short stroke with a coil cut off, I wouldn’t do both though.. ------------- https://www.instagram.com/js_airguns/" rel="nofollow - J S Airguns Air Arms TX200('s) Theoben Sirocco HW77 FWB 300s Webley Patriot One or two others... Current projects: Too many.. |
Posted By: Pauly5
Date Posted: 05 Mar 2025 at 8:57am
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That's good to hear. And depending on the trigger set up, I am guessing it could improve with less pressure on it? |
Posted By: kruzaroad
Date Posted: 05 Mar 2025 at 10:09am
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What about a co2 pauly? You could turn down a tp to a smaller diameter or make an adjustable hammer spring |
Posted By: nunga
Date Posted: 05 Mar 2025 at 9:02pm
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I use my multi pump Canon for the same thing you are talking about. 3 pumps gives you around 450fps which is plenty for sparrows and wont damage stuff if you miss the shot. But if you want to go through the trouble of modding a cheap gun i would not bother with the piston sleeve. waste of time in my books. Just cutting the spring down will be enough. I have done this in the past. if you cut too much off just put some washers behind it till you get the power you want. ------------- 2nd place HP springer - WFTF World Championships 2014 |
Posted By: Pauly5
Date Posted: 05 Mar 2025 at 11:30pm
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I was going to get him to buy the 177 Umarex 850 that was on trademe, but he was too slow. But the Cr600 Co2 is certainly an option too, and if he is happy to pay, i will likely get that. I forgot I had an old Hatsan mod 45 in 177. Just tested it and it's shooting bang on 7 fpe. I don't know how acurate it is, but now I have the two options for him. It's an old club gun that has ended up in my hands.
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