Tuning I Broke Two More Piston Springs!

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Moog

Moog

Member
Jun 9, 2020
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Moogsville, United States
I disassembled my .177 HW95 so I could install the new .22 caliber barrel that I had just ordered. When I took the rifle apart I found that the main spring was broken. The piston seal looked ok. I was very surprised because the rifle is only a year old. My other HW95 is four years old so I figured I'd better check that one too and when I took it apart the main spring in this one was also broken. The piston seal was damaged and will be replaced as well. Both springs broke in the same spot. Three coils down from the end that goes into the piston.

This is what I don't get. A short while ago I did a thread on a Crosman Chinese springer that I replaced the spring and piston seal on for the first time after about 8 or 9 years of use. Yet in my HW guns the spring only lasted 1 year and 4 years on the other one. Am I missing something? I take very good care of my guns. Neither of these rifles have been dry fired or left cocked. I don't use very light weight pellets or shoot the rifles excessively. The one year old rifle has less than 2500 pellets through it. I carefully checked all the internal parts and could not find any evidence of galling or any kind of damage other than the above mentioned parts.

I originally wanted to stay with OEM parts on these rifles but I went ahead and ordered two Hornet springs from James Maccari at ARH. I already have two Hornet piston seals on hand from ARH. Each rifle will get a new spring and piston seal. It's been a journey.
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Springs can be a crap shoot, especially factory springs. In most cases the lowest bidder supplies the springs to the factory. Over the years, especially the past 20 or so years has shown a real improvement in spring quality from after market springs. I can remember 30-40 years back when a factory spring would last mabey 500 to 1 k shots before it broke, as the use of springers grew tremendously, mfgrs had to make better springs and all sorts of aftermarket springs came out. Spring gun design also improved so less preload was used on springs as well as better metals and heat treatment. Today we have numerous quality longer life springs availiable to the public. Unfortunately the factories still buy springs from the lowest bidder. Many mfgrs have changed their design to use very little preload like AA for example. HW guns, while well made have most always used a long spring with a high preload. You will find much better life and performance with an aftermarket spring. By the appearance of your seal, I have to agree on the detonation idea. The goop from the factory is not really a lube, but more of a rust preventative so it is not doing your gun any favors!! Your best bet would be to test fireva new gun, then dissassemble it and clean, polish and quality lube job and you will be surprised how well it works and how much longer spring life will be. 
 
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Bummer about the springs. they only last so long, but one would hope for a few thousand trouble free shots? The piston seal on your 95 looks like mine did. Mine only had 500 shots on it when I took it apart to address the spring noise. Thats when I found the piston seal was cracked clean through. The picture below shows the original after 500 shots(on right). AOA were great and sent me a new seal. After installing the new seal, cleaning and lubricating with moly, the shot cycle was still buzzy and jumpy. Took apart after 100 or so shots and could see the seal(on left) was already slamming the transfer port. THATS when I got the ARH kit. The ARH kit works well. I have a couple Diana 36's in .177 with ARH kits and love em. I have a Diana 38 in .22 with a Vortek that I also love. I find the Diana's way easier to shoot than the HW95 .22. I recently tried a Vortek kit in the 95 and took it out. The cocking shoe was scraping on the steel spring outer guide. I tried to sand down the shoe a wee bit and reassembled but still scraped. So. Back in the ARH went. I have probably 4,000 rounds on that spring so far.
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 I agree with the detonation (dieseling) prescription. Relube with moly. Also Are you 100% sure that the piston AND compression tube are perfectly straight? And does your gun have a tophat at the end of the spring that keeps breaking. Looks like it could be binding. Run your fingers around where the spring sits and feel for any inconsistencies or burrs, and remove them.

And yes across the board on new quality spring, I just got a new 77 se. On order for it 4 seals 3 different springs and 3 tophats. One is adjustable for preload, and a bunch or breech seals
 
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I disassembled my .177 HW95 so I could install the new .22 caliber barrel that I had just ordered. When I took the rifle apart I found that the main spring was broken. The piston seal looked ok. I was very surprised because the rifle is only a year old. My other HW95 is four years old so I figured I'd better check that one too and when I took it apart the main spring in this one was also broken. The piston seal was damaged and will be replaced as well. Both springs broke in the same spot. Three coils down from the end that goes into the piston.

This is what I don't get. A short while ago I did a thread on a Crosman Chinese springer that I replaced the spring and piston seal on for the first time after about 8 or 9 years of use. Yet in my HW guns the spring only lasted 1 year and 4 years on the other one. Am I missing something? I take very good care of my guns. Neither of these rifles have been dry fired or left cocked. I don't use very light weight pellets or shoot the rifles excessively. The one year old rifle has less than 2500 pellets through it. I carefully checked all the internal parts and could not find any evidence of galling or any kind of damage other than the above mentioned parts.

I originally wanted to stay with OEM parts on these rifles but I went ahead and ordered two Hornet springs from James Maccari at ARH. I already have two Hornet piston seals on hand from ARH. Each rifle will get a new spring and piston seal. It's been a journey.
16396113768722125868502.1639611402.jpg






//www.w3.org/2000/svg%22%20viewBox=%220%200%20210%20140%22%3E%3C/svg%3EI have a question. I too was considering getting a .22 or .20 barrel for my hw97 that came in .177. Do you know if the hole from the pressure chamber into the breach is the same size from the factory on a .177 vs .22?
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Pelletsmasher, that's an interesting question. I compared the pressure chamber hole on the one that came as a .22 to the one that came as a .177 and as near as I can tell they are both the same size. I hear about people swapping barrels on these rifles all the time with no problems.

Another member here recently did a thread on replacing a .177 caliber barrel with a .25 caliber on an R9 and it is working well.


 
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Update: I finally got both rifles put back together yesterday and did a quick function check. The new .22 caliber barrel went on the rifle that used to be a .177. The new Hornet springs and Hornet piston seals from ARH were installed in both rifles and of course a proper clean and lube with moly paste was done.

Today I shot them off the bench at 20 yrds to sight in and get a feel for the rifles with the new parts. I must say I'm very happy with the results. Both HW95s gave a very smooth shot cycle. I could not feel or hear any vibration or buzzing at all. I only felt the piston slam forward and then heard the thud of the pellet hitting the pellet trap. A very satisfying feeling. Cocking effort felt a little stiff on both rifles but nothing serious. I'm sure it will get better as the springs break in. I don't have a chronograph so I don't know exact velocities but I got a nice loud "clang" when I hit the frying pan hanging at the 50 yrd marker.

When I originally acquired these two HW95s my plan was to stick with OEM parts but it turned out that the factory springs were totally unacceptable. I think I'm starting to see where you guys are coming from when talking about tune kits. I've only done a limited amount of shooting with these guns since I've installed the new parts what I've seen so far is very encouraging. Thanks everybody for all the helpful advice you have given me on this subject.


 
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Hey, don't feel bad. The mainspring and piston seal on our HW97K didn't last 90 days! I wish I would have spent the extra and bought the gun from AOA instead of Krale. AOA would have fixed it for me. Krale? Not! I would have had to ship it across the pond at my expense, both ways. Live and learn...

I'm not impressed with Weihrauch.

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Remember that most warranty repairs will be replacing the broken spring with another cheap factory spring!!! And will they get all the chips and fragments from the broken spring out?? Forget the warranty and get the rifle properly serviced or do it yourself with quality parts. You will be much better off in the long run !!
 
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