An interesting observation: Royale 500 .25 vs Wildcat .25

Are the barrels the same length? Regulators set the same as well?

Could it be a difference in transfer port size? Or valve, or hammer and spring differences??

And how do these Heavy Kings group out of the WC's,better or worse thank the normal JSB's?

Ted, which bipod do you have on the Wildcat? I've preordered one in .22...the waiting is driving me crazy!

i'll find out for myself by the end of the week how well the impact slings them

Could it be lead build up in the Royale and Bobcat ??? We know you clean the bore but we have seen it in center fire and rim fire. It's hard to get it all out. We have tried a lot different things and ways over the years. Just my $.02

I'd like to see if Ted's results are repeatable across other production Wildcats. Personally I own a Bobcat MK2, but I can fully appreciate the drama that is unfolding here - especially since I just chrony'd my Bobcat yesterday with the 33.95 heavies and wasn't blessed with the same results as Ted. I am pushing .25 heavies at ~795 FPS. Respectable but not as magical as Ted's numbers....

Thanks for sharing Ted! Interesting find! 

FX Wildcat .25
JSB King Heavies MKI
Fill to 240 Bar
7 Mags/56 Shots
Last Manometer reading @ 130 Bar
Note: All Bar readings from manometer on rifle.
​​​
Date: 11/7/2015
Time: 6:56:10 PM
Grains: 33.95
Hi Vel: 822
Low Vel: 800
Ave Vel: 810
Ext Spread: 22
Std Dev: 5​

my wc shoots the 34g pellets at 795 also. but is very accurate with these pellets. the 25g at 875. shoots very well but not quite as good as the heavier pellets. I messed with the hammer spring but didn't do a thing. guy at AOA told me that you are not supposed to move the hammer spring, which I knew was incorrect as ive probably had 6-7 fx guns.

Perhaps the ST barrel of the Royale is a little bit tighter?
The heavy have more lead in the skirt and can thereby braked thereby.


Ted,
Shove carefully a 25gr and 33gr through the barrels, perhaps you noticed more resistant?!

Is the lower the ES , the more true the pellets fly or is it just getting closer to what the reg likes. I haven't shot my bobcat after adj it to see if it is over powered but the best on the chrony is es of 4.38 and sd 1.41 fps av 925.4 of eight shots with jsb exact 25.39gr. ? 

Very interesting to know that. I have a swedish wildcat in .25 (non Fac) for which I have ordered a FAC kit. lets see how does it perform with the kit. I am planning to set it to 910-920 fps with Kings

I no longer have a Royale and haven’t seen a .25 Wildcat, but based upon other rifles, in my view, and if the regulator settings are indeed identical (there is often a small margin of error), the results tend to indicate a different air pressure patterns resulting from different balance of factors around size of transfer ports/dwell times etc; the principal contributing factor in this case likely being differing volumes in the outlet valve chamber. A slightly longer air wave is used more effectively with a heavier pellet, the lighter pellet being out of the barrel sooner and therefore unable to take advantage of the extra air.

I would be more interested/concerned about this issue from the perspective of air efficiency figures, to both improve such but also reduce muzzle noise and theoretically/potentially increase accuracy.