Best Speed for JSB Kings

Macloaded · Mar 16, 2019

I have finally got round to installing a huma reg in my 25 Streamline set to 140bar. I have set up the Rifle to shoot the jsb kings at 910ftps which gives me around 800ftps with the jsb heavies which are good in the wind. The heavies are not as accurate as the Kings in my smooth twist and beginning to think it may be worth dialing back the rifle to shoot the Kings at 880ftps as I feel I am wasting air at 910ftps(rabbits don't notice the difference) and only getting 37 shots, dropping it down should hopefully get me to 40 shots. Before I start fiddling again, what are your views on the best speed for jsb kings out of a smooth twist barrel?

sonny · Mar 16, 2019

The heavy's shoot better faster also, even as fast as the kings (880+) out of my Impact orig ST more consistent/accurately than the kings.

Macloaded · Mar 16, 2019

I was trying the mark one heavies, will try and get some mark two ones to try as kings definitely more accurate at 50yards atm. Don't want to push the streamline much further as don't want a shot count below 30. What reg pressure did you run to get the heavies up to 880?

Spray1Mark · Mar 16, 2019

As above the 33g .25 shoot brilliantly at 880-890 from the Impact with 700mm barrel, 150 bar reg, hammer 15mm.

I get 980 with the 25 kings, but they dont shoot as well at longer distances, best groups come at about 940.

Macloaded · Mar 16, 2019

Sounds like I need to speed them up a bit. I wonder if a smooth twist x barrel liner would help as keep thinking the heavies would prefer that to the smooth twist at closer to 800ftps. I can probably push the streamline to shoot them at 850, I feel further experimentation coming on. Off to buy some mark two heavies tomorrow and despite constant gaels and snow I will be out as the heavies would really put the smack on the wabbits

jwrabbit123 · Mar 16, 2019

I find I like 2 tunes for my jsb 25 gr

low tune is 720fps

power tune is 940 fps

RENVAL · Mar 16, 2019

I have been playing with my Cricket and will say the kings perform excellent @ 915-920 fps, in my gun.

2D1C · Mar 16, 2019

I have all but given up on the 25grain. Both my guns are tuned to 900fps with the KH. One likes the MKII and the other the MKI. The way I'm tuned I can't get below 920 with the 25gn. and at 100 plus they just don't hold for me anyway.

Rj · Mar 16, 2019

My mk1 wildcat preferred the heavies over the kings. It was a laser with them. They should start coming around at 840 and above. 150 bar will get you there.

SeeOhTwo · Mar 16, 2019

Same as RJ. My MK1 .25 Wildcat has almost boring accuracy with heavies at 150 bar...855 fps.

Glenn in Texas

Guest · Mar 17, 2019

Because it is a Diablo, wasted pellet, 850fps is the preferred speed..

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Best Speed for JSB Kings

Macloaded

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sonny

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Macloaded

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Spray1Mark

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Macloaded

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jwrabbit123

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RENVAL

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2D1C

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Rj

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SeeOhTwo

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