.25 Shot String
I finally got around to shooting a shot string with the new .25 JSB Kings in the Walt in Hawaii BBl. So far, they are proving to be more accurate at the longer ranges I normally shoot.
2400-2500 fill (Hard to tell,the gage on the adapter went south, so I robbed one off an old oxygen tank. It’s in Terrible shape) ended at 1400 psi. Shot 35 shots. Whether this is good or bad I have no Idea.
There was no bell curve at all. So I still have work to do. But Very steady decline in numbers. It really helped polishing the hammer weight I got from AF a while back. One of our GREAT Members is making me a heavier hammer. That should really help out!
Here are the numbers I fired one Kodiak for comparison on the first and last shot. All shots were averaged or rounded up or down accordingly. (I’m Lazy!)
Any input is welcomed and appreciated!
Mike
JSB’s————————————-Kod’s
1.1016——————————- 2. 970
1008
1005
999
998
992
989
982
981——-#10
980
974
967
963
960
958
953
949
941
939——-#20
936
933
931
922
924
916
913
907
904
904
898
895
892—————————————827
884—#35
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Viewing 7 replies - 1 through 7 (of 7 total)
That makes sense Jerry. I’m surprised the factory hammer and condor weight is doing so well. Most folks have had trouble with this combo. And too light for most people as well. It gave very erratic results until I polished the Condor weight. I’m betting the new hammer will be even better. It is only 70 grams If I remember right. Isn’t that about what the factory hammer and Condor weight-weigh in at?
Mike
Pab is spot on, you need more air or less hammer. You could fiddle with the spring right now but you’ve already got experience that leads you to avoid going too light on the spring. I don’t think porting the valve would hurt anything but it does add another variable and would drive an even lighter hammer and maybe even a touch lightet spring if you want a broad curve that peaks at 960 or so.
I’d be very careful about closing the tophat too much. If you get to where you are violently bottoming the tophat with a heavy hammer, accuracy will probably suffer.
I suggest you choose a set of operating conditions that best suit your needs and work from there. Is air an issue? If a 2400 psi fill makes your life easier with scuba fills and fewer trips than start looking for a lighter hammer. If air is easy at any pressure, fill it to 3000, back off the spring pre-load and see what you get. You might get lucky or you might have to back off the hammer weight to stay at/under 1000fps at peak.
If I were you, I would think about two configurations for the gun; a consistent high shot count JSB shooting configuration and, a high power larger game hunting, slug shooting configuration. You can do a compromise but it won’t be optimum for either task. Since you have a heavier hammer on the way, you’re probably only a spring away from having the parts you need for two more optimized solutions.
I’d look at cutting down the current hammer and getting a 2400 psi fill to give a nice long flat curve in velocities for JSBs and then using the heavy hammer and more pre-load or a stiffer spring to work with max pressure to give those 9 rings as flat a trajectory as you can get for hunting yotes or big pigs. Seems to me that you can do a fairly quick mod and sight-in to go from one to the other case once you’ve identified the parts and settings required and not have to make big compromises for either usage.
Only a very slightly modified factory Condor valve.
I thought about doing a little more with it, but I figured it would just use more air if I did. I could so some of the porting I did on the Talon valve when I first got it. It worked great. But did use more air. It was very hot for a Talon SS. 😉
Mike
Yeah, I get that. Too little spring compression and it goes all over the place!
Just putting more air in then will give you the bell, but way too high fps… 
As you say, a little less tp and more pressure is a good start. Or lighten the hammer a little.
Are you using a Blod valve?
Thanks Pab, When I lower the spring pressure, it becomes less consistent between shots. Very erratic. I’m thinking less top hat, and more pressure. What say you?
I’ve also noticed less accuracy at 100 yards at the higher fps. It really starts getting accurate in the high to mid 900’s. At around 960 and under she is spot on! 😉
Mike
Knife, to get the bell curve stick a bit more air in the fill. Needs to be not opening the valve flat out to start(lower fps), as pressure drops valve opens fully(high fps), then as air drops lower fps. 😀
If you find that the top of your bell is then too fast fps, lower the wheel(for me less spacer) or lighten the hammer a bit.
Viewing 7 replies - 1 through 7 (of 7 total)
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This is exactly as I do it. I have the gun set up so all I have to do to shoot the big stuff is put in an additional hammer weight in and 1mm extra spacer plus an extra 200psi.
If I want to shoot kods, I just go back to the lighter hammer and keep the fill at 2500.