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Question about MOD 125 spring and gas ram

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Couldn't find an answer anywhere with google so im asking here:

I have a Hatsan MOD 125 Sniper Vortex 22 cal that I want to convert from gas ram to spring.
Since it's difficult to find the parts for the conversion, I bought the standard MOD 125 spring model .177 caliber. The idea to basically swap barrels: Sniper 22. barrel to the action of the standard 1.77 and the 1.77 barrel into the .22 Sniper action.

I think the actions and the transfer port are the same (transfer port hole looks the same dimension, allthough the Sniper action has somekind of sleeve pressed in there. But with the sleeve it looks the same with .177 transfer port.

Now the question is: is the standard MOD 125 .177 versions spring the same that is used in .22 Sniper spring version? And also can I put the Sniper .22 versions gas ram into the .177 action? Are they equal?

The spring that was in the .177 version is I think 43 coils and 353mm long.  Some 125 models might have 48 coil springs from what I can understand from youtube videos. That confuses me.


I am limited to the Hatsan rifles distributed in this country which are all full power rated.
There may be multiple VERSIONS of this rifle sold on your continent so my suggestions may not work for you.

ALL the SPRING Mod125/135 rifles I own use a coil spring with 0.142" wire, ~0.840" OD, and ~44 coils with at least 42 active coils.

CONTRARY to what many folks think (MORE COILS = LESS ENERGY) so I supect 48 coil springs are either aftermarket or are supplied by Hatsan for reduced Muzzle Energy requirements of specific countries.

My Mod125s, after repair and tuning, shoot between 26 fpe and 34 fpe depending on caliber and pellet mass. Small bore 177 usually at the lower end with higher caliber 25 at the higher end.

If this were "my" project I would swap internal part groups.

Vortex + 2-hole-endcap


polymer disc + coil spring + spring guide + steel washer + polymer washer + 3-hole-endcap

(review Hatsans exploded parts drawings)


You could also try to simply swap (barrel + block + cocking-arm) assemblies.

If Hatsan rifles were high precision machined this should work every time. Hatsan rifles in this country are lower cost air rifles. Less than perfect machining and sometimes below average assembled quality are typical for the Hatsan rifles I acquire here. Barrel assembly swap may or may not work well.

Unpinning and hydraulically pressing the barrels OUT of the blocks and swapping only the barrels is possible but the difficulty, special tools required, and risk of damage would be far too high for me to attempt.

I am a big fan of Hatsan air rifles because of the low cost of ownership (here), but I also ENJOY repairing and tuning them to be BETTER... what they SHOULD be from the factory and the best they can be considering the cost and materials used to make them.

FWIW... TP on all my rifles is 4mm x 11mm. No inserts on any of them, just a drilled/reamed hole. I "think" Hatsan may alter the TP size to limit Muzzle Energy in different countries. Some in this country have reported receiving rifles with TPs that were drilled oversize and fitted with threaded inserts (still ~4mm x 11mm with insert). This seems like a valid option for varying ME but I have no hands-on experience with one of these versions.


scroll down here for some Mod125 information...

Thanks mikeyb for very informational answer.
I’ve owned many Hatsans, and this is the first time a dared to dissassemble one (or any airgun as matter of fact) 😊

I will try to make this cheap gun as good as possible. (trigger sears, lubing, deburring etc..) Even though I own also one german and one english springer, I also enjoy my Hatsan 😊. By the way this, just yesterday purcahased new gun had very defective piston seal. Broken from two sides. (I didn’t shoot it even once before takedown)

-These are “FAC” or “full power” guns both, since in Finland we don’t have energy regulations. Only caliber regulations. This .22 MOD125 Sniper Vortex clocked about 27ft/lb when I measured it new a few years ago. I don’t have a chrono anymore so I can’t measure this “project”.

-“CONTRARY to what many folks think (MORE COILS = LESS ENERGY)”  -- that actually got me also. I though it mistakenly the other way.

-“polymer disc + coil spring + spring guide + steel washer + polymer washer + 3-hole-endcap” -- In the springer version .177 there were not polymer disc inside the piston, allthough it is shown in the exploded views of H125. Also there was no polymer washer. Only one metal washer around the spring guide.

But it’s good to know that the spring should be the same no matter what caliber in the MOD 125 lineup. So I think I will proceed with this swap. Chronoing the guns after ofcourse would tell me straightaway how did I succeed but I don’t have a chrono.

The spring from the .177 H125 is 353mm long (13,8 Inch)
The picture from the website you shared looks that the spring is about 15 inch long. This is again confusing.


--- Quote from: Jarkko on April 08, 2024, 08:03:08 AM ---The spring from the .177 H125 is 353mm long (13,8 Inch)
The picture from the website you shared looks that the spring is about 15 inch long. This is again confusing.

--- End quote ---

After break-in new coil springs will be "set"  and free length will be shorter than new. About 13.5"- 14" free length for a "set" spring seems normal to me :-)


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