Kral Information Thread. “Contribute what you know “

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mr_nom_noms_ said:
Not sure if this is someone on here

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Dunno who that is and never seen that video before. I've modified a couple hammers, but the mega/np03 hammer comes with a pretty large diameter spring recess. I've had no trouble getting 32 fpe with stock ports, just higher pressure and large spring. I've never trimmed the spring guide down either, the way it locks back, the exterior rim of the hammer hits the spring seat/adjuster just before that pin bottoms out so I'm not sure that would add anything but worth a try.

I commend this gentleman for going to 300 bar on that aluminum tube though. Now I can lol.
 
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I have used a 3625 psi on a Kratos for two years, and I am experimenting with a 4000 psi fill on my Bighorn.

On the Kratos I have zero problems and did it with Troys blessing. I got the Kratos shooting Kings at 1050 fps.

The Bighorn, a 25 that I shoot the MPMolds .252 44 grain hp, I am using a Pitbull power spring and the hammer Troy modded for the Bulldog spring. I have gotten to a 3900 psi fill and still open the valve and still have the Karl cliff string.

I am using a Talontunes 3625 psi cf bottle, if 4000 psi works out, I will purchase a 4500 psi bottle for safety sakes, either a 580 or a 700.

Regards,

Roachcreek
 
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As a relative newb to tuning air rifles and having never owned a pcp I took the info from this thread and other sources and took the rifle apart and tuned it tonight.

Np03 in .22

2 x orings on the back of the valve to soften the hammer strike

10.4lb spring cut to 2" and the end flattened. Ground flat with a dremel then carefully heated with a torch and squished flat and level

Re assembled and wound the hammer adjuster back inside till it wouldn't cock then backed off by 180 degrees

Fixed the trigger by winding the 5mm nut in to the shaft/ spring behind the trigger then backed it out till it would engage safety

Wound the Allen screw in 1 turn in front of the trigger

The gun is quieter and just kind of 'thunks' which must be down to the orings and shorter stiffer spring.

Trigger feel is great. Nearly no take up a and it breaks like glass, super chrisp.

Took some trial and error but very simple to do all this.

Sadly no chrono but I'll check for accuracy tomorrow.


Thanks to evryone who added to the thread was able to piece it together and get a nice outcome I think
 
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My NP03 really benefited from a bore polishing so I went and polished my standard Puncher's bore as well. It took about 70 shots to break in the barrel again but it now shoots all of the ammo I've tried thus far better than before.

Maybe the best surprise was that CPHPs started to shoot well going over 900 fps. Prior to polishing, CPHPs would only work well at about 750 fps.

These are 5 shot groups at 25 yards from a bench with a bipod shot from my Puncher:

20230105_121424~2.jpg
 
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kuroshio_098 said:
My NP03 really benefited from a bore polishing so I went and polished my standard Puncher's bore as well. It took about 70 shots to break in the barrel again but it now shoots all of the ammo I've tried thus far better than before.

Maybe the best surprise was that CPHPs started to shoot well going over 900 fps. Prior to polishing, CPHPs would only work well at about 750 fps.

These are 5 shot groups at 25 yards from a bench with a bipod shot from my Puncher:

View attachment 320451
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Nice results! After reading your previous post I ordered some bore finishing compound. I see you smeared it on slugs when you tuned your np03

A few questions.

Does it need to be fired with slugs or can you get it from cleaning?

What size slugs did you use? I see they vary in diameter even when designed for 22 cal.

Also is the np03 and magazine equipped to fire slugs or do I need a special magazine?

Lastly, what if compound gets into the port? Will it cause any issues or be blown out?

Sorry for all the dumb questions
 
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mr_nom_noms_ said:
Nice results! After reading your previous post I ordered some bore finishing compound. I see you smeared it on slugs when you tuned your np03

A few questions.

Does it need to be fired with slugs or can you get it from cleaning?

What size slugs did you use? I see they vary in diameter even when designed for 22 cal.

Also is the np03 and magazine equipped to fire slugs or do I need a special magazine?

Lastly, what if compound gets into the port? Will it cause any issues or be blown out?

Sorry for all the dumb questions
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No worries! I see no dumb questions!

Shooting the coated slugs is called "fire lapping". I was a little tentative about using a rod and a cleaning attachment so I tried fire lapping first. I just shot whichever slug my NP03 shot decently which is the NSA 17.5 .2165.

The stock Kral mag works with slugs. Other mags that have a single retaining o-ring are the ones that likely won't work as well. However, I single loaded the slugs in the tray that the Krals come with when I fire lapped because I didn't want the compound in the mags.

After the compound gets into the barrel, there will be some in the barrel port. Since you have to remove the barrel to clean the port, I now believe polishing the barrel with a jag/patch or a mop to be a better option.
 
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got the huma reg installed in the NP-03 refurb and WOW !!
fairly easy for a man with poor vision, but the results are great !!
i set reg to 160bar
15 shots between 864-875 before falling.
18.1gr jsb putting them in a big hole @ 30yrds
perfect for a tractor/truck gun on pests.
 
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gendoc said:
got the huma reg installed in the NP-03 refurb and WOW !!
fairly easy for a man with poor vision, but the results are great !!
i set reg to 160bar
15 shots between 864-875 before falling.
18.1gr jsb putting them in a big hole @ 30yrds
perfect for a tractor/truck gun on pests.
Click to expand...

This is great! Did you order direct from huma?

www.huma-air.com

Kral Arms Puncher NP-03 Tuning Regulator By Huma-Air

Huma-Air pressure regulator for tuning your Kral Arms Puncher NP-03. Will boost your airrifle performance to the highest shot consistency and best accuracy.
www.huma-air.com www.huma-air.com

Seemed to arrive pretty quick?
 
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gendoc said:
got the huma reg installed in the NP-03 refurb and WOW !!
fairly easy for a man with poor vision, but the results are great !!
i set reg to 160bar
15 shots between 864-875 before falling.
18.1gr jsb putting them in a big hole @ 30yrds
perfect for a tractor/truck gun on pests.
Click to expand...
Did you change out the hammer spring at all? Those are good numbers for 18s out of the np03 barrel. The stock spring will eat up some air. If you get a stiffer one you can squeak a bit more out of it. Also, since the regulator is before the burst vent, you can run it up to 250-300 BAR. I run my 280cc regged tube up to 300. Gets 28 fpe for 8 full mags, so 96 shots.
 
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gendoc said:
i have the 10.5lb spring in it.
is it safe to go over 200bar in the NP03 tube ?
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I fill mine to 300 BAR now, just had to delete the burst disk and plug it off. The tube and seals are fine so far!

These guns are built like a tank.

You might like this lil gal I just finished up.

300 BAR fill, 20 shots at 40 fpe with 25.4 air arms. It's a 25 cal, with a 10.75 inch barrel, a Troy Hammer air stripper, and 5 Mrod baffles. Quiet and stout!
20230107_084521.jpg
 
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gendoc said:
very nice gun !!!
i'm going to try 250bar and see what difference it makes in shot count.
i'm really not concerned about the count as 15 shots is enough for a
farm pester. 👨‍🌾
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You should gain a few shots for sure. The power will stay the same obviously. If you want more power without messing with the ports, you could go unregulated with a higher fill pressure and stiffer hammer. The 12.5 Mrod spring would probably open up 250 bar, maybe more. I've had the 16 inch barrels doing 35 fpe with 18s before. Just too loud and the cocking gets rough.
 
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Guns are tested far above the listed fill pressure of course but please stop filling to 300bar on those tubes. It's not safe. A few hundred psi over is no big deal but going 1500psi is going to get someone hurt. The valve and fill assembly seals on a section of the tube that's much thinner than rest of the body.
 
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thammer said:
Guns are tested far above the listed fill pressure of course but please stop filling to 300bar on those tubes. It's not safe. A few hundred psi over is no big deal but going 1500psi is going to get someone hurt. The valve and fill assembly seals on a section of the tube that's much thinner than rest of the body.
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I do kind of cringe when I fill this thing up now. My bottle guns are rated for it, this isn't and I'm sure I'm playing with fire. I'll be backing it down anyhow, just seeing what this little thing could get up to. My goal on the 300 bar gun was 30 fpe I surpassed that by 10.
 
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Boostcreep said:
I do kind of cringe when I fill this thing up now. My bottle guns are rated for it, this isn't and I'm sure I'm playing with fire. I'll be backing it down anyhow, just seeing what this little thing could get up to. My goal on the 300 bar gun was 30 fpe I surpassed that by 10.
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Factory 15-3/4" barrel at 3000psi ported with a smaller diameter poppetvand debounce hammer spring does 24 shots at 900fps with 18.13jsb on the NP03 with no reg needed at well under 20fps ES.
 
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