Kral Puncher NP500 .22 Pellet Selection.

[RoyR]

In March 2024 I purchased this Kral PCP as I've been asked to reduce the rabbit numbers in some smaller country gardens, and where I thought it unwise use the .22LR with 40gn subsonic ammo. The Kral came with a sheet of a pellet test data and that pellet was the JSB Exact Jumbo Diablo 15.89gn @ 5.51mm, so I duly purchase a tin of 500. Weighing 40 of these pellets to check for weight uniformity, I was disappointed to find a spread of nearly 0.7gn with pellets ranging from 15.66 - 16.30gn. Written on the tin lid, it was stated that these pellets were "Carefully Selected", really? I'm a retired Engineer who loads his own CF rifle bullets and the tolerances here were unacceptable to me. I weighed all the 500 pellets and split them into two batches:-15.44 to 15.95gn and 15.96 to 16.38gn. Zeroing each batch, I was then able to achieve 18mm groups at 30Yards.
This set me on a course to try and find a more consistent brand of .22 pellet. I purchased some Test Packs and was astonished to find so many pellets did not work with the Kral, recording many groups greater that 50mm.
I will attempt to upload a jpeg of the list of pellets tried in the hope it will assist other people here at AGF.
Regards
RoyR

 

[RoyR]

Evening Gents, Ladies,

Further observations:-
With my limited 20 types of pellet testing, the RWS test pack proved to be a reliable contender for the Kral Puncher. The RWS pellets appear slightly harder and do not suffer the Waist deformation (being squashed oval) from the Kral Magazine as does the softer lead JSB Exact Jumbo's. Furthermore I've now purchased 2 of the 10-shot magazines by Armstar, and 1 Orange coloured Kral 3D printed magazine from ebay, especially for those softer lead pellets. Both of these magazines fully enclose the pellet, reducing the risk to waist deformation, and currently are functioning very well.
The noticeable Kral "Ring" when firing was also distracting, but I found the barrel shroud contributed somewhat to that “Ring” when pinged with my finger nail. Some heat-shrink sleeving was applied over 3/4 length of this barrel shroud, plus the addition of 4 rubber "O"-rings near the moderator and this has quietened the "Ring" down a little for very little cost.

In the past I've always used break barrel springers. This PCP Air rifle was my first purchase in over 30 years; what attracted me was the function of reduced power, ft/lbs, by turning a knob, exactly my requirement when shooting inside a barn/outbuilding with asbestos roofing sheets. At the price paid I’m pleased with this Kral Puncher NP500, accurate and loads of rounds can be fired from this very large 500cc bottle - 200 and counting.

Regards
RoyR

 

[32:1]

Some time and effort gone into your testing

Every pcp needs a decent pellet test so its not just Kral, with your firearms background Im sure your familiar with rodding the barrel to feel the rifling, Id suggest you remove the barrel and rod a few through from breech and feel if it would benefit from a little polish, it will also show if choke is okay

Krals are decent pcps that are very easy to service and work on yourself, parts are cheap and lots of parts are model interchangeable, so you can barrel swap, calibre change very easily.

Enjoy

 

[Rob Taylor]

Oddly enough, my kral works well with crosman points out to 35 yards (haven't tried much further). It's the only rifle I've known to work well with them.

 

[Boreham]

I have had exactly the same finding with a new Kral mortal X (Essentially the NP500 in a different air tube configuration), initial testing was incredibly poor across JSB/H&N/Bisley Magnums/QYS, with similar grouping results to yourself, upto 100mm + the barrel was incredibly filthy, with loads of transport grease which took a lot of cleaning.
The same issue with the magazines, i returned the rifle to the retailer and they tested and initially had good results at 15yds but also called me to say the magazines in this box were particularly bad, one was deforming every brand of pellets, they are conducting some further tests this week prior to returning to to ensure it has 'settled' after initial poor grouping (also checked the shroud and end cap alignment).

My initial test revealed the rifle preferred a slightly heavier pellet, mine is a .177 and the 9.56gr and above seemed better, and to your observations the QYS were very consistent on weight variation with the lowest spread, JSB also very poor (interestingly my HFT500 will group under 8mm with the same JSB Exact so the Walthar barrel is a lot less fussy)

The Kral barrels seem to have a good write up and i look to have a bit of problem rifle but hopefully it will be resolved by the RFD this week, coupled with 2 new mags (i also went with the 3D printed type and an SSL), the RFD is replacing the std mags but they do seem to be relatively poorly made and on return the barrel will get attention with a bronze brush to ensure it is free of any remaining crud.

Thanks on the details for the audible 'ping' i was thinking it was the hammer spring, maybe a carbon shroud replacement will dampen this

 

[RoyR]

Thank you 32:1, that is good sound advice.
I did swab out the barrel after purchase because I know many new rifles have a protective coating of lube on the rifling, and yes, I may indeed start looking at some modifications, when th Kral is out of warranty.

Now I've found about 4 pellets that consistently group under 20mm at 30yards, I will be chrono'ing the speed of these pellets at 25yards to ascertain the retained knockdown ft/lbs power of these pellets. Muzzel velocity ft/lbs is a useful guide, but it is the down range terminal ft/lbs that is of most interest to me. I will do this test and report back, when and if the current English weather allows?

If of interest my chronograph is the Caldwell Ballistic Precision Pro with 6 volt IR light bars.

Regards

RoyR

P.S. just seen the replies from Rob Taylor and Boreham, Thank you for your input.
Appears these Kral barrels are individuals ( no two the same?) and require their own individual pellet.

 

[32:1]

Also take note of the fill pressure when testing as some pellets may perform in a certain FPS window

 

[32:1]

I cut 6” off my barrel as I wanted to ‘carbine’ it, I also fitted a 300cc carbon bottle as I carry it around, a few little tweaks inside to make it better suited to sub12, its a brilliant little pesting gun and its so light and pointable now

 

[RoyR]

" Also take note of the fill pressure when testing as some pellets may perform in a certain FPS window",

Morning 32:1,
Thanks for your comments.

Is this another variable that has to be factored into the pellet data? I was believing that the Kral Air Regulator System which sets this airgun below 12ft/lbs would provide a Constant Pressure, and so cater for the lowering in bottle reservoir pressure; the Kral fitted pressure gauge has a "Green"-range from 100bar to 250bar. Is it wrong then to assume that this "Green Range" is the reliable "working range" of the air regulator? If it is wrong, it opens up a route of endless combinations and possible outcomes.
Just the differences in a tin of pellet weight that I've encountered, of up to 0.9gn low to high, is enough to contend with.

OK, just checked the Kral bottle pressure and it's hovering just above 150Bar. When It gets near 100Bar I'll do a test with my chosen .22 pellet, have the bottled refilled to 250Bar and redo the test.

Thank goodness I have my reliable .22LR for those longer range shots on the rabbits.

Regards
RoyR

 

[32:1]

The np isnt regulated, its called self regulation due to the fact the air pressure allows the valve to move at various distances and times and the pressure in the bottle forces against it and how much air escapes obviously

Your rifle will have a power curve of some sort like non regulated guns, you should shoot a full fill and record shots as this will give you and idea of what fps your getting at what psi and then find your so called sweetspot.

Most Krals seem to shoot full fill fps which gradually decreases with fill pressure drop, with a couple of tweaks you can extend the useable shots and get a better curve where your fps rises a little as pressures drop and then gradually falls as fill pressure gets lower

Each pellet will have an optimum fps

Here’s a fill test from a while ago so you can see whats going on

 

[RoyR]

Morning 32:1,

I was wrong believing the Kral had some sort of 12ft/lbs regulation, as you correctly made the point it does not; I should have researched this better before my Kral purchase. However, this situation is changing because I now see that Kral have released a GEN 2 version of the Kral Puncher WITH a proper regulation valve.
Thanks for your power curve / sweet sport graph, most enlightening.
I've now researched the differences between regulated and non-regulated rifles and it would appear that if the reservoir bottle pressure is kept within a certain range then most of the mitigating differences can be kept to a minimum, especially as in my circumstances where most of the air rifle work will be at short range, usually under 35yards. From my research of other Kraal Puncher user’s findings, a typical 140bar to 230bar appears to give a decent performance of optimum accuracy and most shot count.
My local dealer charges just £5 to refill this 500cc bottle to 250Bar, so I was going to use this service and not purchase a 5L bottle for around £210. However, in the light of your new information regarding "sweet spots," I will be purchasing a bottle and maintaining a bottle pressure of around 140bar to 230bar and see how effective that is.
Thanks again for everyone's input.
Will return to this thread when I've completed some 25yard chronograph tests to establish terminal ft/lbs of my chosen pellets.

Regards
RoyR

 

[Mr Blue]

My kral also likes rws

 

[RoyR]

Morning Gents,
I have concluded my pellet test with the 6 pellets that best suited my Kral for accuracy at 30 yards, with the chronograph terminal ft/lbs measured at 25yards. It was interesting to me that domed head-type pellets lost the least fps while the Hobby (flat head) and Hollow Point pellets lost the most fps with their obviously lower BC. The Superdome pellets were the abnormally being 88fps slower, so I tested another 6 pellets and got same results? Perhaps the lower Bottle pressure of 130bar is the cause?
The clear winner, best suited for my Kral rifle, was the RWS Superfield, retaining the most ft/lbs at 25yds with best accuracy. The JSB Exacts were a second choice ONLY if each pellet was inspected for waist damage/deformity and then pellet weight; these had nearly a 1gn weight difference between low & high in my 500 tin, so as explained in my first thread, I weighed each pellet and split them into low and high weights, 15.44 to 15.95gn and 15.96 to 16.38gn.

32:1’s interesting reply regarding Sweet-Spot bottle pressure for Non-Regulated rifles, certainly had me thinking on this subject, so I chrono’d the 6 pellets again with the lower bottle pressure of 130Bar @ M.V. 2.5ft, I was somewhat happily surprised to find similar results to a bottle fill pressure of 210Bar; some readings were actually slightly higher. As yet do not know what happens in between these pressures.
From my perspective, suffice to say Kral appear to have got this Non-Regulation system about right.

Anyway I’ve attached a chart of my test results, which may be of use to other folk here.

Morning Danny 3522,
Nice grouping, looking similar to my RWS Superfield! What distance was this achieved at please?

Regards
RoyR

 

[32:1]

Nice work

Now you need to extend the range to your maximum shooting distance and see which pellet delivers best accuracy out that far as you’ll see another 10yds can make or break a pellet choice

 

[Mr Blue]

25yards also buddy

 

[RoyR]

Further Pellet tests.
Had heard/read recent good reports of the JTS Dead Centre .22 pellets, so purchased 250 of 18.1gn and 250 of 16.08gn.
Much to my surprise, having weighed 100 of each, found there was only 0.1gn Low/Hi difference in both weights, exceptional!
The 18.13gn Low/Hi measured 18.04 to 18.14gn, and the 16.08gn Low/High measured 16.04 to 16.13gn. For me this is a fantastic find because with these close tolerances it means I do not have to weigh the complete tin and segregate into Hi/Lows. I have not yet fired these pellets to access accuracy/groups, but looking favourable given the close weight tolerances. I just hope the Krall "likes" these pellets. Also purchased the Air Arms Field 16gn and Heavy Field 18.gn to test.

Update.
Anyway, have finally concluded the tests for the two JTS Dead Centre and two Air Arms - Diablo Field & Diablo Heavy Field
As stated in earlier post, was impressed with the JTS pellet weight consistency of 0.1gn; the best I have yet come across!
The Air Arms pellet consistency was average with pellet weight variable low to high, of around 0.28gns
My Kral Puncher certainly preferes the pellets of around16gn weight, but the JTS 18.1gn had the best grouping of the heavier weights tried, probably due to the excellent pellet weight consistency. The JTS 16.08gn is on par with my 1st original chosen pellet, the RWS Superfield but slightly better grouping at 30yards.
JTS definitely have it here and are worth considering for their weight consistency, contributing to my better groups.
Hope this assists some people here.
Regards
RoyR

 

[RoyR]

Afternoon Gents,
A further update on the JTS pellet weight consistency.
Today I received two more 250 tins of the JTS 16.08gn .22 pellets, to confirm that my original first tin pellet weight consistency was not a fluke.
Happily I can confirm that again there was just a Low/High variation of about 0.1gn:- 16.03gn to 16.12gn - excellent news!

Unlike other brands of pellets tested, which I found to be up to a massive 0.9gn Low/High variation, I now do not have to weigh these JTS pellets and seperate into two or three weight group tins.
Keeping pellet weight to closer tolerences assists me in better down-range shot groupings.
Hope this helps someone?

Regards
RoyR

 

[Womble-With-a-Rifle]

Excellent data Sir I doff my cap to you
It’s possibly saved me a lot of chilly time on my own range this windy chilly autumn
I await the arrival of my Kral puncher shadow
Again thankyou for your time consuming work

 

[ukzero1]

@RoyR

I noticed you have tried the Baracuda Hunter, but don't ignore the Hunter Extreme. The Hunter did't do too well in my HW100kt but the Hunter Extreme works wonders and is now my 'go to' pest control pellet. I think you may be surprised.

By the way, nice data collection.