AirMaks Arms Caiman MK1 regulator problem

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tsakula

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Jan 28, 2016
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NY, United States
Hi. Can you please suggest any good aftermarket regulator for Caiman X mk1 in 25 cal? Its creeping so much. And giving super different speeds all the time.

It is giving 230 FPS difference. Depends on the mood of the gun. UA sent me to the Airmaks because they told me they have no spare parts. And Airmaks told m its discontinued. Please suggest something. Its making me crazy already
 
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tsakula said:
Hi. Can you please suggest any good aftermarket regulator for Caiman X mk1 in 25 cal? Its creeping so much. And giving super different speeds all the time.

It is giving 230 FPS difference. Depends on the mood of the gun. UA sent me to the Airmaks because they told me they have no spare parts. And Airmaks told m its discontinued. Please suggest something. Its making me crazy already
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Search the forums. I believe there’s a fix for it. Something you can do yourself. I almost grabbed that Caiman myself. It’s a common problem on the early caimans. You should be able to get it sorted out.

Good luck.
Rob
 
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I just bought a Mk1 Caiman X for cheap at Utah Airguns. Had heard about reg issues with the first series of guns, but was O.K. buying it after reading about the Weevil Mod, developed by AGN's own member weevil. Check out this thread and it might help you keep your OEM regulator instead of purchasing a new one.

Weevil Mod
 
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I just did the weevil mod this afternoon to my new-to-me, NOS Caiman X. I didn't have the same problem as these Gen 1 Caiman's are known for: Instead of slowly decreasing in speed over the shot string, my gun shot real slow at first, and over 50+ shots rose almost 600 fps! Yikes - starting at 357 and slowly but surely heading up to 950 before it stabilized just for a bit and then started dropping off as the cylinder pressure dropped. So likely a very creepy reg from the start, holding the valve from fully opening until pressure in the cylinder dropped.

Since this is a NOS gun, I was wondering whether the reg might just need some time to start functioning properly. But I figured WTH, I'll see how it does when it can breathe properly. So I did the Weevil mod and things are working great now!

I set the hammer spring for about 910 fps with 25.39's (my gun is a .25 cal) and the accuracy at 25 yds where I have tested it so far is one hole. Spread over the entire shot string was a little high as 40 shots pushed the air capacity a little much (starting from only a 240b fill). But still only 26 fps with an SD of 5.1. And with that speed difference there should really be no POI change out to at least 40 yards over the entire 40 shots.

Thank you weevil for your airgun acumen, and for publishing such a great fix for the Gen 1 Caimans!
 
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I do not know about a 25 but the Huma of my 22 caliber Caiman X came set at 100 bar and that pushes 18 grain pellets easily over 900 fps. It needs a much lower regulator setting than my other PCPs. (my gun needed the weevil mod and also needed excess silicone grease taken off the bellville washers and a little added to the O-ring on the regulator adjustment shaft). Works great now. ES came down with more use.
 
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Degassing a Caiman is a function of which version you have. Early ones had a tool that came with the gun that allowed you to depress the valve a little bit (open it) to degass the gun. Mine did not have this tool so I had to contact Utah Airguns who explained why. They put on what I consider a normal degassing screw instead. Getting to it is somewhat involved but once you are there it is pretty simple to degass and adjust the regulator. You have to take both portions of the stock off first. The bottom is a couple screws. The top is held on by tapered pins on early ones but mine has two screws for the top portion too. The scope has to come off to take the top part of the stock off. Another difference is the safety location. Early ones had the safety in the back of the gun but mine is above the trigger. That pin has to come off, however, the safety pin that slides side to side for the lower part of the stock to come off. There are two screws inside the trigger guard that have to be loosened. The smaller one you can access through the trigger guard and it has to be backed off a lot. The larger one is for the tension on the pin and you don't have to loosen it but the pins come out easier if you loosen it like 1/4 turn.

With the stock off, on mine you unclamp the airtube from the rest of the gun. There are two screws at the back of the airtube for this. The degassing screw is under the front one. Open it slowly until air comes out. You may have to loosen it some more to get all the air. Once you are degassed you screw off the back end of the airtube and pull the regulator out. You will need to put a bolt or something into the threaded hole in the regulator to pull it against the O-ring tension holding it in place. I used a tap last time I did this only because it was handy and the right thread. A bolt would be less brittle and therefore a better idea. But you shouldn't have to pull very hard. I don't remember if there is a lock nut but basically you just turn the adjustment screw you will see once the regulator is out. Humas have a paper tape to give approximate settings, I have not seen that on others. 1/4 turn should be safe. To go down, you want to turn clockwise like you would to tighten a normal screw.

It probably sounds more complicated than it is. The only unusual thing is the clamshell stock. I had no instructions the first time I took it off and still got it done.. I assume the first generation Caiman is the same except for no degassing screw on the airtube. I believe the manual has some discussion of how to degass (for the first generation, not the second).
 
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