FX What is the limit of crown mk2?

Gambler · Nov 20, 2023

I have a mk2 i want to "adjust". As is stands now I have pin probe, huma spring and tungsten weight. Reg is at 155bar and I shoot .25 33.49 KO mk2 at 950fps with good groups.
BUT my tune is hopfully way off since i only get around 25 shots from 250bar down to 155, but thats is maybe how it has to be to push the slugs at that speed? Should I be able to reach that speed with lower reg pressure?
I tried to lower and get speeds around 900 but the slugs didnt like that somehow.

Jlowe · Nov 20, 2023

They say you can go to 170bar with the tungsten hammer weight.

Gambler · Nov 20, 2023

But then again my shot count Will go Down even more, a 580 or 700 bottle would give me some more shots atleast.

Jlowe · Nov 20, 2023

That’s what I did. I put a 580cc tank on my Crown MKII .25cal.

Long_Gun_Dallas · Nov 20, 2023

Have you tried backing off the hammer at 155 bar? Either way I think air consumption will be quite high at that power level.

Ranchibi · Nov 20, 2023

Also barrel length can help with speed if your are not running a 700mm......

Gambler · Nov 20, 2023

I run 600mm, so my best bet it a bigger bottle. But I see some bottles are rated to 300bar, does the internals on the crown handle that?

Ranchibi · Nov 20, 2023

Don't know about the pressure ratings for it's internals but a 700mm barrel should give you 20-30 increase in fps over the 600. My friend went from a 380 to a 700 and got an increase of 100fps on same tune....your mileage may vary but you will see an increase in fps with more shots available being more efficient.

jps2486 · Nov 20, 2023

Try lowering the reg pressure. You are wasting air.

Gambler · Nov 20, 2023

jps2486 said:
Try lowering the reg pressure. You are wasting air.

Yeah, but I wont be able to hold the 940-950fps the slugs like, but ive waiting on my heavy liner now, so maybe the slug Will be stable at lower speeds with that.

MongooseV8 · Nov 20, 2023

Personally I wouldnt go over 150Bar on any factory FX reg. Plenty of FX videos and literature suggesting 150Bar as the max to prevent premature wear or failure. So in my opinion that is the furthest you can push a stock FX Crown.

Jlowe · Nov 20, 2023

In my experience of the Crown MKII shooting JSB KO's the MKII's are much more stable at lower speeds than the MKI's. I had them shooting 885fps out of my 500mm .25cal barrel extremely well, which was not the case with the MK 1's.

jps2486 · Nov 20, 2023

Gambler said:
Yeah, but I wont be able to hold the 940-950fps the slugs like, but ive waiting on my heavy liner now, so maybe the slug Will be stable at lower speeds with that.

You might be surprised. I would gradually lower it until the velocity drops off. Then you are getting the most energy for the air expended.

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FX What is the limit of crown mk2?

Gambler

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