what is the Crown .22 prefer FPS with JSB 18.1 gr?

Forums PCP Airguns what is the Crown .22 prefer FPS with JSB 18.1 gr?

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    Max115
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    hello there,

    just wondering what is the best and preferred FPS you have found for Crown .22 with JSB 18.1 gr to have tight groups at 100 yards?

    thanks.

     

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    DennisB
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    I run my .22 crown at 830 with 18.13 JSB

    Den

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    Max115
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    Thanks Dan.

    i haven’t done any adjustments other than using the Max setting with 18 gr at 878fps since I got the fun new a week ago. Groups at 100 yards were not very good.  I will trying lower speed and see if the groups get any better on my next range time.

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    toku58
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    Max115

    hello there,

    just wondering what is the best and preferred FPS you have found for Crown .22 with JSB 18.1 gr to have tight groups at 100 yards?

    thanks.

     

    Each gun/barrel will be a little different. Approximately 900 fps is a good starting point. Then go through and sort all your pellets for consistent weight and condition.

    shoot a crap load of pellets .

    Find out what your gun really likes. considering that you can have a 10 fps spread, and the human factors, just get it to the point that you are happy with the groups.

    Any pellet will start to destabilize at higher FPS speeds. (It's just the limitation of their design)

    But the idea is to get it up to it's maximum FPS to reduce the time in flight and give it a flatter trajectory. 

    I would assume that you have a crono? So go out and have fun!
    Good Luck!  Be safe!

    Have a Great Day!

     

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    Max115
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    Thank you Toku. I do have a chrony and I will put in more range time to find my optimal FPS.

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    SocalTrail
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    I played around with the speeds I shot the 18.1 JSB’s at for quite a while. After having great accuracy shooting then at 920 from my Airwolf MCT, I tuned my WAR Flex to shoot them at 915 with phenomenal accuracy. I had several 5-shot groups at or under 1” at 100 yards at this speed. I didn’t notice any weird spiraling or accuracy degeneration until I hit almost 960-970. I don’t do anything special to my pellets and don’t sort them. I always used to stick  to the 850-880 range until recently, and I won’t go back until I see negative effects. The ST X barre on the FX guns may not play so nice with the diablo pellets at those speeds, but that might be able to be remedied with the different twist liners they claim to be releasing soon. As mentioned above, I would get your range set up on a nice calm day and keep turning the speed up until you see some issue pop up. For me it was very evident.  I went from 1” – 1.5” groups consistently to 4” groups within a matter of 10 FPS. Find that threshold and de tune a bit to give you some wiggle room. I had my best luck tuning at 100 yards because I could actually observe the pellet flight through the scope. If you can’t swing a 100 yards, 50 yards would be the minimum I would tune at. 

     

    When i I had my crown, I had it shooting the 18.1’s at 880 with pretty good groups at 50. I didn’t have any spiraling or pellet destabilization. 

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    Max115
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    Thanks SocalTrail for the in-depth findings.

    I was able to do a bit of testing today after work.

    I took Toku’s advise and tune down the speed from 870 to 830 from Max to 5. My 50 yards group with 18 gr was getting tighter the more I shoot.  I was hitting the 3/4” dots pretty good with a bit of wind.

    I also tried the 25.4 gr JSB at 50 yards at Max 740fps and achieved similar results.

    next testing I need to do is to stretch out further and see if the groups are decent at those speed and setting.

    thanks for the feedback guys. I enjoy learning the fun and receiving advices from you.

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    Max115
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    Edit. I meant to thank Den for the 830 FPS.

    here is my 50 yards group of 5 shots at 830fps.

     

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    Max115
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    SocalTrail
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    Good work, your on your way.  Check out some of the tuning guides for the impact / Crown here in the forum. It’s a true balance you need to find. On one hand you want to tune all the aspects of the rifle for max efficiency. Most of the time those tuning values will lend themselves to the best chance at accuracy, but not always. Once you find the “harmony” of the gun like Ted likes to say, fine tune your velocity for the best accuracy and pellet your running. From the looks of our groups, those are good for sure but not even close to what I’ve personally experienced and seen the crown capable of.  When you get it dialed in, you should be able to put together a 5-shot group under .5” at 50 in good conditions prettt easily. To me, 830 seems a bit slow for the smooth twist and 18.1’s.  I would start there and slowly go up until you see your groups hopefully tighten up. Pick a good morning or evening with no wind and go to town.  Good work, your definitely on the right track. 

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    Max115
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    thank you ST.  only way to find out is to experiment different combinations to find the "harmony" as per Ted.

    I am confident that I will get the tight groups soon of later as this Crown has the potential.  I have a Daystate Regal XL .22 and this rifle can do 1/2" at 50 yards easily.

    the joy of airgunning is so satisfying.

    cheers!

     

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