Hatsan mods
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=107
Printed Date: 19 Oct 2025 at 9:52pm
Software Version: Web Wiz Forums 10.14 - http://www.webwizforums.com
Topic: Hatsan mods
Posted By: nunga
Subject: Hatsan mods
Date Posted: 27 Mar 2014 at 2:14am
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I have started to strip down my Hatsan mod125 last night. I will be doing two things to it. First be doing a mod on the single stage trigger it has as this is the older pre quattro trigger version. Second i will be down tuning it to around 800fps which will involve ether cutting the spring or fitting one of my gas rams to it. But I think the gas ram will be the way to go. My reasons for this are simple. The hatsan is a very heavy gun and with a less powerful spring/ram installed there should little to no recoil and if my trigger mod works the way i want then it will be a very accurate air rifle. I will start on the trigger tonight and post some photos and more info on what i will be doing tomorrow. |
Replies:
Posted By: nunga
Date Posted: 27 Mar 2014 at 2:52pm
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Well here are some pictures of what i am up to. I have got the trigger apart and this is what it looks like side on put together and resting on the outside of the housing. Note there are no springs installed. The trigger is in the "cocked" position. The trigger blade and the first lever it contacts are plastic. the other two top bits are metal.  This is what it looks like when you pull the trigger and the trigger is not cocked. as you can see the contact point where the plastic lever pushes the first bit of metal. This is the part where i will do my mod. I will be taking part of the plastic corner off to move the contact point further up the metal. this will reduce the amount of force needed to move everything and give a smother trigger action.  |
Posted By: (pink)MIST
Date Posted: 27 Mar 2014 at 4:33pm
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Watching , interested to see this as it progresses .... ------------- NZAFTA President 1st place HP springer - 2014 WFTF Worlds 1st place HP springer - 2014 Nats AA TX200 MK111, Optisan Viper 8-32x60 JSB. VMach, TbT, maestro design. |
Posted By: nunga
Date Posted: 28 Mar 2014 at 2:08pm
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After some thought I decided not to do the trigger mod just yet. I came
to the conclusion it would be a waste of time before i got the spring
sorted out as the spring will play a big part on trigger weight as well. So time to get the spring sorted. First i pulled the thing apart again.   With the spring out it was time to cut it down. I took two coils off to see how it went.  Next i needed to grind the end flat. This is very important when cutting down the spring.  Next i needed to get a file and smooth the end down and polish it. This is also very important. If the ends of your spring are rough they will not be able to twist as the spring compresses and you will get excessive noise from your spring. this is what the finished product looks like  Next i put the gun back together and put it through the chrony. What a surprise it is still pumping out over 1100 fps ! i was not expecting that. Part two to follow shortly. |
Posted By: nunga
Date Posted: 28 Mar 2014 at 2:25pm
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Next i pulled the gun down again. This time i am working on the front spring guide. I do not want to cut the spring down anymore so i will take some metal off the the spring guide. As you can see it has a lot of meat to take off and it is big and heavy. this goes inside the piston.  So i put it in my lathe and took around 15mm off the end. I also took the sharp edges off from the factory machining at the same time   With the spring all ready to go it was time to put it back into the gun. First thing i noticed was the spring only sticks out around 10mm now and i had no problems putting the spring back in with out the spring compressor. Back on the chrony and we now have 950fps perfect :) Tomorrow i will apply a idea i had to take the "twang" out of the gun from the spring and i will be cutting down the barrel to around 380mm then i will show you all how to crown the barrel as well. With a bit of luck it might be ready for the Wellington shoot but we will see. |
Posted By: nunga
Date Posted: 03 Apr 2014 at 8:14am
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Haven't forgotten about this, I will try to get some more work done on this tonight. The weekend came up faster than expected and ran out of time. And by the looks of it this weekend is almost here now as well... |
Posted By: nunga
Date Posted: 09 Jun 2014 at 9:59am
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Right got some time today so i did some more on the Hatsan. Today i installed the Gasram and tested it. I machined up some new parts as the old ones are made of plastic and will be no use. I decided to make this out of steel and not alloy.       As you can see i have taken out the safety latch and there is a square hole where it used to be. I am going to be making a new trigger for it over the next month or so i wont be needing that anymore. Next was to put it through the chrony and see how it goes. I used some crosman pellets to test it and it is pumping out 1071 fps which is still way to fast. But there is little recoil now and it is much smoother to cock now. with some heavier 10.4gr pellets should bring it down to under 800fps. But it is tea time now and getting dark. so it can wait for another day now.  |
Posted By: (pink)MIST
Date Posted: 09 Jun 2014 at 12:28pm
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At that speed it'd sound like a .22 RF going off. Def agree 8.4s too light , might not have a spring to break anymore, but they'd fly all over the place. 10.4s will bring the MV down and should therefore gain some consistency in point if impact. (Not only that, but as a hunting pellet, good speed + good weight = good terminal energy , not very scientifically written, but the bunnies and possums will understand it ;) ------------- NZAFTA President 1st place HP springer - 2014 WFTF Worlds 1st place HP springer - 2014 Nats AA TX200 MK111, Optisan Viper 8-32x60 JSB. VMach, TbT, maestro design. |
Posted By: Davey
Date Posted: 10 Jun 2014 at 4:14am
| Or you could just file half a mm at a time off of the gas ram stem :-) |
Posted By: nunga
Date Posted: 29 Jun 2014 at 8:45am
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Doing some more work on this as well tonight. Will post some pictures later with some detailed work on my new trigger i made for it :) |
Posted By: nunga
Date Posted: 10 Nov 2014 at 12:52pm
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Just picked up my new .25 barrel today. tomorrow i will be getting everything ready to replace the standard .177 barrel. I will also pump up the pressure in the ram to get the power up so this will be my possum buster. I hope to get up and around 30fpe by the end of the week. Watch this space! ------------- 2nd place HP springer - WFTF World Championships 2014 |
Posted By: (pink)MIST
Date Posted: 10 Nov 2014 at 4:16pm
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Omg this forum has life again!! :) 30fpe in .25 cal should make a dent in a possum , they're gonna need Kevlar to stand a chance lol ------------- NZAFTA President 1st place HP springer - 2014 WFTF Worlds 1st place HP springer - 2014 Nats AA TX200 MK111, Optisan Viper 8-32x60 JSB. VMach, TbT, maestro design. |
Posted By: nunga
Date Posted: 11 Nov 2014 at 3:47pm
Started on the barrel tonight. Stripped the gun down and took the barrel off ready to pull apart. Next i took the muzzle brake off because it kept spinning on the barrel. I put the back end in the vise and got the vice grips on the muzzle end and un-screwed the barrel.  Next i measured everything up and started machine the new barrel to fit. one thing i noticed is the quality of the Hatsan workmanship is average at best and they have a lot of clearance on their parts and have put a lot of sh*t in to full up the gaps. I will make my new barrel to better standards and will be a better fit when done.   Finished the machining and cut the thread and it fits very nice now. This is the finished product.  That will do for now as the walking dead is on and i need to watch that :) Tomorrow i will work on the Ram and crank the pressure up a bit. ------------- 2nd place HP springer - WFTF World Championships 2014 |
Posted By: nunga
Date Posted: 12 Nov 2014 at 12:24pm
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Before i start mucking around with the ram im going to put it all back together and see what it is putting out. I made the barrel longer than i needed it. I am in two minds if i will keep the barrel choke on this or cut it off. I am after full power and im unsure how much the choke will slow down the pellet as it leaves the barrel. And since this gun will be only for shooting up in trees out to 30 yards max im not sure if i will even need the choke. Got to do some more research on that one first i think. ------------- 2nd place HP springer - WFTF World Championships 2014 |
Posted By: Pauly5
Date Posted: 12 Nov 2014 at 4:02pm
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Yea good to see some life in the forum so Nunga can take some life outta possums. Good stuff, I like reading this stuff. ------------- |
Posted By: nunga
Date Posted: 13 Nov 2014 at 2:20am
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I put the gun through the chrony this morning before i left for work. It is not so bad. It did pretty good. I got H&N 19.6 pellets flying out @ 670 FPS thats around 20pfe. I will put 400psi extra into the ram to take it up to 1900psi and see how that goes. It will be a fine balance to get the power just right. ------------- 2nd place HP springer - WFTF World Championships 2014 |
Posted By: nunga
Date Posted: 15 Nov 2014 at 2:46am
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I have decided to full up the gas ram myself. I normally send them away to Auckland and they send them back at the pressure that i have asked for. But this can take a week or so to do and at $80.00 a pop it gets a little on the expensive side. So i am going to build myself a pump and a adapter to fill the rams. ------------- 2nd place HP springer - WFTF World Championships 2014 |
Posted By: (pink)MIST
Date Posted: 15 Nov 2014 at 3:10am
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More kiwi ingenuity at its finest, pics of course right? :) ------------- NZAFTA President 1st place HP springer - 2014 WFTF Worlds 1st place HP springer - 2014 Nats AA TX200 MK111, Optisan Viper 8-32x60 JSB. VMach, TbT, maestro design. |
Posted By: nunga
Date Posted: 17 Nov 2014 at 8:32am
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I started work on the full adapter for the ram this morning. I decided to use alloy as i have lots of this to choose from. I am making it big. First machine and drill the guide hole.  Next machine out so the shaft can fit through.  Next machine out for the main body to fit and machine o ring groves to seal the main body and shaft.   Next fit o rings and check compression to see if it will seal with the high air pressure im going to be pumping in.  Next fit the gas ram to see if all is good.  This is as far as i have got so far. Stage one finished. I will mill a flat peace into the top of the round adapter and drill the fill hole but i cant do that till tonight. so i will post some more later. ------------- 2nd place HP springer - WFTF World Championships 2014 |
Posted By: Adam
Date Posted: 18 Nov 2014 at 7:33pm
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Ian we should chat about your trigger group mods. What you have described is "one way" of modding it, but IMHO is not "the best way". Have done a couple of the 125's before, and lots of the 55's, 60's, etc. If you have the equipment I'd recommend looking at replacing all plastic levers with steel, and possibly replacing the existing sears with better material instead of the cast muck metal used. Instead of altering the long lever, try changing the angle of the sears at point of contact. Makes a huge difference. Make a brass replacement trigger blade and add in two adjustment screws for a true 2 stage. You can the end up with a trigger group that is a joy to use rather than a gritty jerky stiff POS. We should chat at length before you get too far into it.
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Posted By: nunga
Date Posted: 19 Nov 2014 at 1:23pm
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i'll give you a call next few days adam, Im really loving this new barrel. I decided to put a scope on the gun did a super quick zero at 20 yards put a few pellets through the chrony and found it was putting out 720 fps now with the 19gr FTT pellets. Just as i was putting it away I saw three rabbits sitting in the filed across the river around 80 meters away. I nailed all three of them, the power of these .25 pellets is fantastic the little bastards didnt know what hit them. Really looking forward to the higher pressure im going to pump into the ram. I would say 100+ meter kills no problem with this once it is finished. ------------- 2nd place HP springer - WFTF World Championships 2014 |
Posted By: nunga
Date Posted: 19 Nov 2014 at 2:46pm
Did the finishing up of the adapter so it is ready to use.  Next i have started the frame to hold the pump. I found an old go-cart frame i started to make a few years ago so i decided to cut it up and use the parts.    This is as far as i have got so far. ------------- 2nd place HP springer - WFTF World Championships 2014 |
Posted By: nunga
Date Posted: 21 Nov 2014 at 3:27pm
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Done some more on it tonight. This is the plan on how i will (hopefully) fill my rams. As you can see bellow on the picture i have got a $29.00 car gas strut from Supercheap auto. The plan is to use this ram to top up the current gams i already have. I am going to cut the base off the new strut and make an adapter to fit from the base of the car gas strut into my fill jig. The car strut is about twice as long as my gun gas ram so there should be enough air in there to top up the gun. I plan on getting some bathroom scales to measure the pressure it takes to compress the rams i can then work out how much more i need to put in for it to work without over pressurizing it.  As you can see it doesnt look pretty and i will clean it up and finish off the welds over the weekend ------------- 2nd place HP springer - WFTF World Championships 2014 |
Posted By: nunga
Date Posted: 04 Dec 2014 at 3:04am
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I just thought i would give you a quick update on my progress. Everything is on hold for now as i have screwed my Calf mussel and im out of action probably till after Christmas. They said might take 3- 6 weeks before i can walk unaided and around 3 months for a full recovery. So my goal is walk in 2 weeks and all better (and gun finished) by Christmas :) ------------- 2nd place HP springer - WFTF World Championships 2014 |
Posted By: Pauly5
Date Posted: 04 Dec 2014 at 6:15am
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Man that's bad luck. Are you sure didn't shoot yourself in the calf? So the gas ram pumper upper thing you're making, does it pump up the rams with a gas? therefore you must have a supply of that gas to pump into the rams you are adapting, and you are using the bigger car gas strut as a way to push the gas in? Sorry I am just making sure I fully understand what you're doing. Very clever. ------------- |
Posted By: nunga
Date Posted: 04 Dec 2014 at 6:41am
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The super dooper gas ram pumper upper thing-a-me- giggy im making will pump normal air into the rams to increase the pressure. I am doing this because the air that you breathe has 78% nitrogen in it anyway and the rams are filled with 100% nitrogen to start with. so topping them up with normal air will not harm or affect them in any way as the ram will still have over 90% nitrogen in it anyway. I plan to use a old fridge compressor to pre-charge the pump (car gas strut) to around 3 - 400psi that way it will cut down the time needed to pump. there will be a one way valve to keep the adapter pressurized. But Yes i am using the bigger gas strut as a way to push air into the ram :) ------------- 2nd place HP springer - WFTF World Championships 2014 |
Posted By: nunga
Date Posted: 15 Mar 2015 at 4:29pm
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Finally got the ram to a high pressure.it is a lot harder to cock than before.the first shot through the crony with 31gr pellets came out 702fps second 690 that's up over 32 foot pounds so I'm happy with the results so far. ------------- 2nd place HP springer - WFTF World Championships 2014 |
Posted By: (pink)MIST
Date Posted: 17 Mar 2015 at 8:06am
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And a new breed of bunny slayer is born :) ------------- NZAFTA President 1st place HP springer - 2014 WFTF Worlds 1st place HP springer - 2014 Nats AA TX200 MK111, Optisan Viper 8-32x60 JSB. VMach, TbT, maestro design. |
Posted By: nunga
Date Posted: 17 Mar 2015 at 8:24am
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yeah, I did notice that there is a funny sound coming from the gun when firing heavier pellets. almost sounds like air leaking from somewhere, maybe the breach seal or something. I do know i need the stock off you sooner rather than later as this plastic stock is almost fallen apart now. I might come for a drive this coming weekend and pick it up. ------------- 2nd place HP springer - WFTF World Championships 2014 |