Kral Information Thread. “Contribute what you know “
- Thread starter Perle
- Start date
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.
until it got down to 120bar, then i stopped testing with that spring
a very bad air hog !!
changed to 10.5lb spring and it was about the same "cliff" and just a small pig,
but it was there.
i need to find a regulator for it
i tested that spring at 170-150bar fill to get an idea of where a reg needs work around.
better ES and accuracy about 160bar @ 867fps.
watched a video on utube about a kral puncher and a lane regulator with very good install
instructions.
i will be checking altaros regs next.
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My 10.5 lb spring arrived with a bunch of other stuff not messing with the spring yet based on the above. No scope rings yet but I can see it's nice and balanced with that 3-9 × 40 . This is the sumo installed. Wouldn't want to go bigger and doesn't feel as nose heavy as I thought it would
The bipod is magpul
The bipod is magpul
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i'm taking a chance on a reg/plenum system from lane for the puncher line.
hopefully its inline with the NP-03
hopefully its inline with the NP-03
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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.
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 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
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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
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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 go the other route with these guns. I port everything, install a heavy spring, and raise the fill pressure about 30-50BAR to accommodate for the huge spring. Only thing I've had is a burst disk pop, and that was on my 300 BAR bottle jumbo. These guns are friggin tanks and over engineered.
I usually gain more power and shots that way. I've had my 177 np03 get over 1100 fps with crosman premiers 7.9 grain.
My pro 500 has an np03 barrel in it with a 250 bar fill and heavy spring. No porting at all and I get 32 fpe for over 100 shots.
You get them set up right and it'll run like a regulated gun but with better power. In experience with these guns, running a regulator will limit power potential. You get enough spring behind it and enlarge the ports, you'll get things moving fast!
If you really want power and not worried on length, get the mega or knight barrel for it. Longer=power.
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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.
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.
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Well, I don’t know if this is THE way, but here’s how I do a “B Staley” modification:
Remove stock
Back out Hammerspring adjuster til it pops out
Remove Hammer spring
Remove the screw at the pivot point on the sidelever (Bigger screw at the top of breech, not the linkage screw)
Remove the “keeper” screw on the side of the hammer (visible thru the slot on the side of the action)
You should be able to drop the hammer out the back of the action, if not, pull the trigger to drop the sear and it should slide out the back.
Take two (or three) # 112 O Rings from the Harbor Freight metric O Ring assortment and slide them into the hammer spring chamber.
I use a small wooden dowel (the stick end of a pistol swab, actually) to Guide the o ring down to the face of the valve.
Take your time placing them against the valve face, then another on top of the first.
You’ll find that two o rings basically make up the depth of the hammer face which strikes the valve, so using three you would need even more speed when throwing the hammer forward because the hammer will have to compress one o ring completely before it makes contact with the valve poppet stem protruding from the valve face.
The key with the Kral setup is having just enough spring to open the valve but not so much as to cause hammer bounce. That’s where the changing of the hammer spring becomes so important. The o rings help to avoid a full on hammer face to valve face collision and therefore act as a de-bounce device, but too much spring will still bounce the hammer with two o rings.
I wanted to get 20 FPE out of this little carbine, so that’s where I stopped.
The stock hammer spring is to long and light in my opinion. I’ve seen hammer springs from the Turkish guns “take a set” in a short amount of time and lose their initial compression strength. Have had good luck with offerings from Gardner Spring Out o fTulsa, OK. It’s Part number 36479G. Search Precision Compression Springs and sort by length (2”).
Once the o rings are in place, simply slide the hammer back in and install the “keeper“ screw in the side of the hammer.
Install the pivot point screw
slide hammer spring into back of hammer.
I set the hammer spring adjuster 3 & 1/2 turns in.
Sounds a lot harder than it is when a fella writes it all out.
Porting works well too, but you can always take the gun back to stock form with this method.
Good Luck!
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Quick couple of mags this morning to get the scope zeroed and loving this package already. Only from lanai to backstop at 26 yards. Have to wait for a fill probe adapter then I can stretch it out further
Some great mods on this thread to look at now
Some great mods on this thread to look at now
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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.
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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.
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.
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I have 5? I think it's 5 Krals lol... probably another 2 guns in parts laying around!
They have certainly checked off some mid range guns that I wanted because these will definitely do what I need and more. Sure they're not a daystate or FX, but from the groups I get to ones I see posted of a $2500+ rifle and theyre the same or better, yeah I'll pass thanks.
I will own either a dreamline or huntsman revere one day, and a brocock bantam. Everything else is off list for now. If something sexy comes along that's semi automatic and reliable, it'll be added to the list.
oh yeah...
Got more parts on the way for another Kral build!
Stay tuned!
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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.
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Top notch traditional style rifle. I don't think I've ever read a bad post about them either.
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