Tuning Kratos 300 bar fill

[Meanadidas]

I just purchased a Benjamin Kratos with carbon fiber bottle and my question is: Is it possible to fill to 280 - 300 bar now and if not, what would I need to reinforce for higher working pressure if possible?

I have not seen the internals of a Kratos yet however I am assuming it's not the same as their Marauder rifle which I am very familiar with. I am wanting to push JSB Monster .22 Redesigns 25.39gr @ 920fps or higher

 

[dizzums]

i would imagine if its regulated rigjt at the bottle why not .. otherwise im not so sure the internals are designed for that much ... but positve it would need to be tuned to it ..

 

[Meanadidas]

I don't have a regulator on it.

 

[JimNM]

Do not push it past the limit. That is a very bad idea. In fact that's how people get hurt by exploding guns.

 

[pnwairgunner]

Like dizzums has said, you’ll have to tune for it. That’s going to involve either using the factory hammer spring and making the adjustments or installing a heavier spring to open the valve under the added pressure. Next will be modifying the power wheel port to allow more air to flow to the barrel. 
What is your speed now with the 25gr at 3000 psi? It might be possible to get it up to speed without increasing your tank pressure by modifying the valve and opening the power wheel port, but Troy Hammer is going to be the guy with the most experience with Kral type airguns, so you may message him for advice. If you can do it with a lower pressure then I’d say that’s the smart route to go, since it’s going to save wear and tear on your compressor. 

 

[CyberDyneSystems]

Kratos internals are specced for 200 bar. Someone swapped in a bottle rated higher, but the rifle has not changed. I would not try this.

 

[pnwairgunner]

As far as “internals” go, the only part of the rifle that is subject to any added stress from a higher tank fill is the valve assembly (and obviously the tank itself). The burst disk location is shown in the pic above. I’m not sure what the burst disk pressure is designed to rupture at on it, but I have over filled a Cayden a considerable amount (like 4000psi) by mistake and the disk didn’t burst. What DID occur was the tiny o ring on the poppet was unknowingly damaged and after degassing to the 3000 psi mark the Cayden started having a “brraaap” type sound when it was fired as air leaked past the valve stem and the air pressure pushed the hammer part of the way back and the hammer spring would then push it back into the valve stem, causing the whole thing to repeat over and over about 50 times in a second. A very exaggerated hammer bounce situation. Re-sealed with new o-rings and it’s back to normal.
So with that being said if I were attempting to up the power on a Kratos I would first try opening the power adjuster port and maybe using a lighter return spring in the valve and adjusting the hammer spring tension as needed to tune it and staying at the lower fill pressure.
You don’t automatically gain power with higher pressure. The air is going to be restricted by the size of the port it’s traveling through. For instance: A Benjamin marauder with a bigger exhaust on the valve and a bigger transfer port filled to 1900 psi can make the same power as the same rifle filled to 3000psi with the factory valve and t-port size. And it does so with a lot less hammer spring power which makes the rifle a lot easier to cock the bolt than someone who has installed a crazy powerful hammer spring to force the valve to stay open longer. More psi doesn’t mean much in this case except it’s easier to fill up the 1900psi gun. 
Anyway, I got carried away with my typing there. Good luck on your Kratos. 

 

[Meanadidas]

Thanks all for the feedback. I will probably keep it as is and enjoy the extra shot count and put the need for higher power into another rifle either already equipped or capable of higher output. 

I really like the Kratos and was hoping to juice it up some without outgrowing the economic viability and long-term safety over usage.

 

[darylm]

I wouldn’t fill past the spec’ed pressure level. If the cf bottle is a 580cc, you’ll definitely increase shot count. But you could always get a 700cc cf bottle from Alsafe (there are several threads on this topic). That would REALLY bump up your shot count, and keep within the guns recommended pressure.

 

[thammer]

The valve is the same as the Super Jumbo. You're OK to the 250 bar just as it's rated. Your issue is porting size not the pressure. I think you only have 5/32" porting. You'll have to drill the transfer port to 3/16" which is about max for the power adjuster then drill and tap the breech for a new 5mm barrel retaining screw. That plus a little hammerspring work should get you there but it's only a 19" maybe 20" barrel so that's why you have lean on airflow and hammerspring to get there. 

 

[CyberDyneSystems]

Thanks all for the feedback. I will probably keep it as is and enjoy the extra shot count and put the need for higher power into another rifle either already equipped or capable of higher output. 

I really like the Kratos and was hoping to juice it up some without outgrowing the economic viability and long-term safety over usage.

I love mine too! I have a CF bottle waiting to be swapped in when i get some time, just for the extra shots and reduced weight at the front.