the 12.5lb spring gave me over 900fps with 18.1gr in 1st 3 shots then continued to drastically declinegot the springs in, 1st i installed 12.5lb spring. adjustment screw only went in about 1/3 of what the stock spring did. i'm also adjusting down until no coil bind.
hope to find a good velocity with the 18.1gr, but 1000fps with the cpd 14.3gr is fine too accurately !!!
testing in the morning.
I was one of the early Puncher Breaker owners a few years back. Pushed that gun really hard for about 3000 rounds til the poppet stem broke. Will Piatt built a new poppet and stem from dimensions I had given him. Put another 3-4000 rounds thru that gun til I bought a balanced valve from Jefferson State. Put that in and once I got the right hammer spring in place (with a B Staley mod) I can get upwards of 90 shots on a fill pushing JSB 18’s at 925 to 950. Although not quite as accurate as my Taipan or Raptor mini, its darn close to 50 yards.
Decided to take the plunge on a Kral NP-03 when PA started selling the re-furbs. I wasn’t expecting much for power as its a smaller tank and a shorter barrel than the Puncher Breaker, and I was right about the power aspect, BUT - as received from PA I shot 86 shots over the chronograph from 693 up to 733 and back to 689. Just 15-17 FPE but HOLY COW!!!! That’s a LOT of shots from 3K down to 1.1K. I pulled the Hammer and dropped in two 112 O-Rings for a B Staley mod then used a 0.48”x0.055 X 2.00 Spring from Gardner Spring (P/N 36479G). With 3 & 1/2 turns in on the hammer spring that combo yielded 46 shots 789 to 842 and back to 796. 20FPE up to 22.4 FPE. Could fine tune it a little but I’m pleased with those numbers. Accuracy is just under an inch @ 50 yards and with a Buck Rail moderator on it’s very quiet. I learned early on that Karl’s are decent but can be darn nice with some elbow grease and simple mods. The NP-03 is no exception.
I have done a BStaley mod to my Benjamin Prod using 4 orings.I was one of the early Puncher Breaker owners a few years back. Pushed that gun really hard for about 3000 rounds til the poppet stem broke. Will Piatt built a new poppet and stem from dimensions I had given him. Put another 3-4000 rounds thru that gun til I bought a balanced valve from Jefferson State. Put that in and once I got the right hammer spring in place (with a B Staley mod) I can get upwards of 90 shots on a fill pushing JSB 18’s at 925 to 950. Although not quite as accurate as my Taipan or Raptor mini, its darn close to 50 yards.
Decided to take the plunge on a Kral NP-03 when PA started selling the re-furbs. I wasn’t expecting much for power as its a smaller tank and a shorter barrel than the Puncher Breaker, and I was right about the power aspect, BUT - as received from PA I shot 86 shots over the chronograph from 693 up to 733 and back to 689. Just 15-17 FPE but HOLY COW!!!! That’s a LOT of shots from 3K down to 1.1K. I pulled the Hammer and dropped in two 112 O-Rings for a B Staley mod then used a 0.48”x0.055 X 2.00 Spring from Gardner Spring (P/N 36479G). With 3 & 1/2 turns in on the hammer spring that combo yielded 46 shots 789 to 842 and back to 796. 20FPE up to 22.4 FPE. Could fine tune it a little but I’m pleased with those numbers. Accuracy is just under an inch @ 50 yards and with a Buck Rail moderator on it’s very quiet. I learned early on that Karl’s are decent but can be darn nice with some elbow grease and simple mods. The NP-03 is no exception.
The tubes on the np03 are aluminum vs steel on all the 280cc and 330cc tubes. I don't think the reg will fit, the inner diameter of the tubes are different.i'm taking a chance on a reg/plenum system from lane for the puncher line.
hopefully its inline with the NP-03
The o-rings go in between the hammer and back of valve to cushion the hammer blow. Gives you a more consistent shot string, smoother shot cycle, and more efficient on air. Gotta get the spring rate just right to reap the benefits and an adjustable striker would really help level it out to almost regulated strings. Makes them a bit quieter too since using less air per shot.I have done a BStaley mod to my Benjamin Prod using 4 orings.
I now have 2 Kral NP-03 now in different calibers.
flatpick65 please explain how you did the BStaley mod to the Kral NP-03.
Where did you put the orings?
Did you try any other oring combinations?
etc
Well, I don’t know if this is THE way, but here’s how I do a “B Staley” modification:I have done a BStaley mod to my Benjamin Prod using 4 orings.
I now have 2 Kral NP-03 now in different calibers.
flatpick65 please explain how you did the BStaley mod to the Kral NP-03.
Where did you put the orings?
Did you try any other oring combinations?
etc
Take the tube out and should be able to stuff them in there in front of the hammer. Or take stock off, take hammer screw out from left side, take the spring adjuster and spring our, rack the cocking lever and it'll pop out the back. Put the o-rings in from that side, and reinstall the hammer. Done.I am not after power.
I am only shooting at targets about 60 yards away.
I have a stronger spring in the .22 NP-03 which allows me to overfill to about 250 bars.
I had a burst disk which I have replaced with a small piece I cut from a pellet tin.
Now I get at least 4 mags (50+ shots) at about 20 FPE from 250 bars (3600 PSI) down to about 140 bar (2000 PSI) .
I will have to open up my NP-03 to see how the BStaley mod orings go in.
thats how i'm going to do it when i install the Huma reg i just ordered....Take the tube out and should be able to stuff them in there in front of the hammer.
I have 5? I think it's 5 Krals lol... probably another 2 guns in parts laying around!Interesting to see how many different ways the Krals can be tuned. Thank you for all the tips.
The NP03 has a great form factor for me. Pair that with the performance and it erased some more costly PCPs off my wish list.
Looking forward to it!Got more parts on the way for another Kral build!
Stay tuned!
Top notch traditional style rifle. I don't think I've ever read a bad post about them either.Looking forward to it!
I can see why you like the Revere. It is higher on the short list of PCPs that are "maybes" for me.