Hatsan 125 Spring Replacement

[PensacolaHusker]

Where can I buy an aftermarket spring for the 125 and will a 135 spring fit the 125? Thanks

[Madd Hatter]

Mikey B will be along to give the 411. I think they both use the same spring.

https://vortekproducts.com/products/142-wire-840-od-spring

[mikeyb]

0.142" wire, 0.840" outer diameter, ~0.556" inner diameter, ~44 coils.

It is a BIG SPRING!

I recommend the actual Hatsan coil spring if they have them in stock.

The "Hatsan" coil spring for the Mod125 and the Mod135 are the same part. The larger swept volume of the Mod135 compression tube and the slightly heavier Mod135 piston can squeeze a tiny bit more energy from the same spring.

Fill in the form

https://hatsanairgunsusa.com/customer-service-form/

 and request an invoice for the specific parts you want. Hatsan will usually respond in a few days. You pay for the parts plus S&H, then Hatsan will ship them out to you a few days later. ASSUMING they have the parts in stock.

The only other option I am aware of is Vortek. I use the full length unfinished end spring because I wanted to finish the ends myself. For most folks ordering the "finished" ends will be a better option.


https://vortekproducts.com/products/hatsan135-patroit-power-spring ($29)

or for the open end version...

https://vortekproducts.com/products/142-wire-840-od-spring ($29)

You will NEED a strong stable SPRING COMPRESSOR with at least 3" of travel. For NEW unset springs it may be better to have at least 4" of spring compressor travel.

Do not try to use ANY type of clamp that contains plastic parts in the force-path. I made that mistake but got LUCKY. No injury or rifle damage but the clamp was trashed and walls got DAMAGED from fast flying parts!

Good Luck!

[Kragman1]

'88 Buick Regal front end spring should do it....   🤣

[PensacolaHusker]

Thanks for the replies. Very helpful. I have disassembled the 125 before and you're right, you do need a sturdy compressor. I currently have an aftermarket gas piston that started shooting erratically recently and was going to swap it with a spring and make a new spring guide. I was going to try an aluminum  and a delrin to see which works better. Hopefully it's just the piston seal that went bad.

[mikeyb]

Thanks for the replies. Very helpful. I have disassembled the 125 before and you're right, you do need a sturdy compressor. I currently have an aftermarket gas piston that started shooting erratically recently and was going to swap it with a spring and make a new spring guide. I was going to try an aluminum  and a delrin to see which works better. Hopefully it's just the piston seal that went bad.

Piston seals don't last forever but they are cheap.

The piston seal is the Hatsan "Med" for 29mm ID compression tubes. That's all the Mod125 series rifles.

https://hatsanairgunsusa.com/product/medium-plunger-seal/
 $4.95 and 7 in stock right now.

Did the rifle come from the factory with a coil spring?

If YES, all you need is the spring and a spring guide. Make the guide yourself. Length can be up to ~7" and it should be a snug fit on a relaxed spring. The short loose fit Hatsan spring guide is nearly useless. https://michaeljbernard.wordpress.com/2020/02/24/2020_02_23_hatsan_mod125_spring_25_refurb/

If the rifle came from the factory with Vortex air spring it likely has the 2-hole end plug. You will want to get a 3-hole end plug for a Mod125. I ordered 3 pieces many weeks ago and am still waiting for HatsanUSA to restock them (from Turkey).

Apparently HatsanUSA only had the 30mm 3-hole end plugs for the Mod130/135 series rifles which they sent me by mistake. I very specifically ordered the Mod125 3-hole 29mm plugs. Trust me when I say the 30mm end plugs DO NOT FIT the 29mm compression tubes! They did have the Mod125/135 coil springs in stock and I did receive the correct coil springs.

[PensacolaHusker]

How snug should the guide be? I have 1/2" delrin and aluminum rod? Which do you think would work better? And luckily the gas piston I am replacing called for the 3 hole plug so I already have it.

[mikeyb]

How snug should the guide be? I have 1/2" delrin and aluminum rod? Which do you think would work better? And luckily the gas piston I am replacing called for the 3 hole plug so I already have it.

Spring dimension tolerances vary. Some springs vary from one end to the other. I custom sand my guides to fit very SNUG in one end of the relaxed spring. I have to twist the guide INTO the spring and twist the guide OUT of the spring. Many times the custom guide WON'T fit into the other end of the spring.

I'm experimenting with 14mm drill rod now (results later) as a potential spring guide material. That would theoretically be a 0.551" OD guide, but it may be too large and need more sanding than my other guide.

My "normal" spring guide is made from 1/4" schedule 40 black steel plumbing pipe with some washers TIG welded on one end. Theoretical OD is 0.540" but that pipe has a welded seam and a coating and is almost never perfectly round. I usually need only a light sanding to get a good friction fit with my springs. Don't worry, the springs aren't perfectly round either. The "tuning" part is fitting a specific guide to a specific spring.

When the spring is preloaded 3" inside the rifle the guide fit RELAXES to just snug (perfect IMO). When spring is fully compressed the guide fit should be loose (no friction). We WANT the guide to "grab" the spring near the end of the piston stroke so the guide can suppress spring vibrations.

My guide is ~7" long verses the Hatsan guide which is about 3.75" long.

I would not use Aluminum here. I think Delrin would make a good spring guide but 1/2" OD is too small. I think the OD needs to be in the range of 0.525"-0.550", but the exact number DEPENDS ON YOUR SPECIFIC SPRING.

[PensacolaHusker]

Good info. I think I'll get some 5/8" delrin and sand it down to fit snug inside the spring. Thanks again.

[mikeyb]

Likely not common but 9/16" = 0.5625" which will need much less sanding/machining than 5/8" (0.625") to get to the 0.525"-0.550" needed to fit a Hatsan Mod125/135 spring.

Also, if the material is available in metric dimensions a 14mm (0.551") OD starting point would require even less sanding.

Just a suggestion to check for other raw material dimensions.

[PensacolaHusker]

Thanks. You are the man. Lol

[PensacolaHusker]

I made a 6 3/4" guide out of steel and ordered the 9/16 delrin. I'll try the steel first since it's done and I'm waiting on the delrin to arrive. The steel rod is a little loose so I'll have to use the shrink wrap tune. I will let you know how it goes

[PensacolaHusker]

Installed the steel guide and it's shooting well, so far. It has a solid thump with the steel rod and is getting anywhere from 23-26 fpe. Maybe it'll get more as the new piston seal wears in. My other 125, that has the bad gas piston, I'm going to try the delrin and compare the two. Thanks for all your help.

[mikeyb]

What calibers are your Mod125 rifles?

[PensacolaHusker]

The one I just worked on with the steel guide is a .22 and the other is a. 25.

[Novagun]

I am a bit confused here. The internal diameter of the spring is .5 inch. The external is .75 inch  how can you make a guide from .5 inch sanded to size . I thought the collar on the end of the guide,protected by a steel washer kept the guide centered in the piston tube and in place in the spring and that is important
My reading is that your fabrication is just a rod but it is possible I got it wrong
My

[Novagun]

Too right, I was confused. .Just remembered that the spring guide on a Hatsan is different to a Gamo .

[PensacolaHusker]

No worries. The steel rod was a bit small so I used the electrical shrink wrap method. The 9/16 delrin I ordered is too big and will be sanded to size. So far it's shooting well. I'm getting quarter size groups at 15 yards. Unfortunately every time I try and post a pic it says file too large.

[mikeyb]

No worries. The steel rod was a bit small so I used the electrical shrink wrap method. The 9/16 delrin I ordered is too big and will be sanded to size. So far it's shooting well. I'm getting quarter size groups at 15 yards. Unfortunately every time I try and post a pic it says file too large.

The default image resolution on my Android cell phone camera is NICE but far too large for posting images here. My phone came with a fast easy image editor that allows me to CROP the image to focus on the subject (eliminates wasted space) and SCALE the image to something like 2000x1000 pixels or less. That "edit & save" takes LESS than 20 seconds.  If my edited image is in focus and has good brightness the ~2000x1000 size usually has MORE DETAIL than is needed for posting here AND the file size is small enough to pass the Forums maximum size limits for images.