AirMaks Arms Airmaks Katran barrel swap

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j24

j24

Member
Nov 17, 2023
29
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Tampa, FL, USA
After using a few PCPs at a show, I think the Katran will be the first quality quality rife I add to my collection. I’ve found a few used models with various accessories, which is the route I prefer at this early stage of my entry into the sport. The commonality seems to be that they are all L or X versions, which are the long barrel models. While I wait for the 10 days to pass before I can PM on the classifieds to make an offer here, I am taking the opportunity to learn a bit more.

I’ve seen videos on how to swap the Katran barrel and bottles, but does anyone carry various barrels? I’d like the option to go shorter for back yard pests.
 
J24,

I’d have bought the Katran in the classifieds already if it were an SC. Love the look of that gun, I just want it to be super compact.

Instead I just bought an AGT Vixen which is a Long. Even though I wanted a short but it was a deal I couldn’t pass up.

I have a lathe so there is always that option. But I’ve ibeen making enquiries regarding buying just a short barrel.

I want a rifle in .177 that points like a Red Ryder, but can push a pellet at least 700fps, and is near silent.
 
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Update: I emailed Mike at UA about this question and like everyone has said, he goes up and beyond. Thank you Mike! He messaged Airmaks and they responded that they DO sell barrel swaps. However, Katran’s are build specific. Meaning, if you purchase a .177 you can swap the barrel to a .22 or .25. BUT, the power output of the regulator stays tuned for the .177 you purchased.

My first thought is that I could try it. I’m at a lower power and pushing a bigger slug. But then it dawned on me that owners of the larger bore may have an over power issue if they purchase a smaller caliber barrel.

More research needed.

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j24 said:
Update: I emailed Mike at UA about this question and like everyone has said, he goes up and beyond. Thank you Mike! He messaged Airmaks and they responded that they DO sell barrel swaps. However, Katran’s are build specific. Meaning, if you purchase a .177 you can swap the barrel to a .22 or .25. BUT, the power output of the regulator stays tuned for the .177 you purchased.

My first thought is that I could try it. I’m at a lower power and pushing a bigger slug. But then it dawned on me that owners of the larger bore may have an over power issue if they purchase a smaller caliber barrel.

More research needed.

View attachment 410693
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I do not understand why they say that, because you can simply adjust your regulator. I adjusted mine from the factory 120 bar, to about 145 bar very easily.
 
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Bladebum said:
I do not understand why they say that, because you can simply adjust your regulator. I adjusted mine from the factory 120 bar, to about 145 bar very easily.
Click to expand...
This reads very strange to me as well. Are there aftermarket regs that work in these guns that any members have tried? I would think that this Huma reg would enable one to remedy the issue of power limitation in a caliber swap (within a reasonable range). https://www.huma-air.com/AirMaks-Katran-Tuning-Regulator-by-Huma-Air
 
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There is probably a youtube on changing the Katran regulator. Sub 12 airguns did a complete disassembly and regulator rebuild. What I remember from it is the regulator is inside the air tube (on the non-bottle versions) and has to be removed to be changed. You have to drain all the air, of course, before opening the gun up this way, the gun comes with the tool for that. My P35s require the same sort of disassembly to change the regulator. It is definitely possible. I wonder if there may be an issue with the transfer port size and possibly also the path between the transfer port and the barrel port. My P35-25 had a barrel port, transfer port, and the passage between them that was about 75% of bore size. Changing the barrel would only change the barrel port. Having a really big transfer port and passage would tend to make the 177 powerful but it might also result in a relatively high ES and standard deviation. If you went the other way, started with a 177 and went to a 25, you may have a power issue. I don't know how guns like Avenge X, FX, and RTI prophet deal with this.
 
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I have been on a rampage with the tiniest Katran. You can read the story here. The reg is easily adjusted and it’s useful to tune the valve return spring.

AirMaks Arms - Katran SC setup and review: now with quick tune instructions!

Skip to bottom of post #6 for a quick guide! Fellow connoisseurs, This thread will focus on a newly purchased Katran which was purchased as a ratter for my neighbor. However, due to an incident in the setup, it seems destined to be mine, in exchange for my Atomic XR. We’ll get into this...
www.airgunnation.com www.airgunnation.com
 
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weevil said:
I have been on a rampage with the tiniest Katran. You can read the story here. The reg is easily adjusted and it’s useful to tune the valve return spring.

AirMaks Arms - Katran SC setup and review: now with quick tune instructions!

Skip to bottom of post #6 for a quick guide! Fellow connoisseurs, This thread will focus on a newly purchased Katran which was purchased as a ratter for my neighbor. However, due to an incident in the setup, it seems destined to be mine, in exchange for my Atomic XR. We’ll get into this...
www.airgunnation.com www.airgunnation.com
Click to expand...
Great info and a very nice read. Thanks.
 
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j24 said:
Update: I emailed Mike at UA about this question and like everyone has said, he goes up and beyond. Thank you Mike! He messaged Airmaks and they responded that they DO sell barrel swaps. However, Katran’s are build specific. Meaning, if you purchase a .177 you can swap the barrel to a .22 or .25. BUT, the power output of the regulator stays tuned for the .177 you purchased.

My first thought is that I could try it. I’m at a lower power and pushing a bigger slug. But then it dawned on me that owners of the larger bore may have an over power issue if they purchase a smaller caliber barrel.

More research needed.

View attachment 410693
Click to expand...
LOL, if you did only change the barrel from 177 to 22, the power would go up because larger calibers are more efficient in using air!
 
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weevil said:
LOL, if you did only change the barrel from 177 to 22, the power would go up because larger calibers are more efficient in using air!
Click to expand...

Based on what you shared, I decided to go ahead with the swap from .177 to .25. I reached out to UA to broker it, and AirMaks had a similar reply as last time. With the added disappointing news: a cost of +$500 before shipping.

"Hi Mike . The customers needs buy not only barrel , probe and regulator too . Because regulator has tuned in low power in .177, for .22 and especially for .25 he needs more power. So set barrel +probe + regulator is $519.99 . If you have any questions don’t hesitate to ask me again. Best regards, ..."

The probe too?? Perhaps I am not understanding something?
 
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Well, that's bad news. I think at that point, I'd sell and buy another of what I wanted. I have a .177 Katran, and I was not aware it couldn't be tuned differently. I'll have to have a look see. I will say, I have NO thoughts of changing it. Airmaks must really put a lot of effort into tuning them, because mine is one of the accurate, and consistant rifle I've ever shot.
I was getting frustrated trying to tune my R10 the other day, so I broke out the Katran and fired two clips (34 shots) over the chron to test the chrono (certainly not the Airmaks), and got an avg of 917fps ES of 9fps and a 1/2" 30M 34 shot group! My rifle is so consistent, that almost every time I shoot it, and it can be a month or a week or whatever, the first shot is always 922, and then it settles into a long string of high 9teens. It is simply an amazing rifle. And YES, Mike at UA is the man to deal with. I bought mine from him, it was new, used in one match and then sold to me. I couldn't be happier with it. If I had some other need, a different velocity or whatever and this rifle would do, I'd buy another tuned to do what I wanted.

PS: I just did a quick YT search and now I remember, the Katran reg is adjustable, (I was sure it was, but worked on too many guns to remember), so you might need to do some fiddling, or even a spring or belleville change out, but I'd bet it can be done......just not cheap. Withing caliber I'm sure you can change the tune in the gun without too much trouble.
 
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