Dissapointed in JSB King Extra Heavy 25's

[KarlH]

Just got in 12 tins of 300 this afternoon, my cricket is around 60 foot pounds and likes the H&N 31 grain baracudas with rare flyers. It also likes the H&N grizzlies if I sort them throwing out any that have any visual defect no matter how small.  If I don't cull the grizzlies I can get fliers two plus feet out at 100 yards, culled visually it is rare to get a flyer and normal 5 round groups are under 2 inches at 100 yards, just blows throwing out around 15% of the pellets.  Nothing I have tried under 30 grains does well in my cricket and everything over is at least not bad, I've seen the sunlight glinting off 25-28 grain diablo type pellets that were more than 5 feet off target at 100 yards. 

I Felt confident ordering so many JSB's given their reputation, plus got 3 tins free and free fedex shipping so the price was right.  Well, I ripped off a few at 100 yards with my cricket bull pup and was sure I could chrono them without any worry of hitting the chrono at that distance, put in 2moa adjustment right on scope and held 2moa higher.  Two 10 shot strings, one had extreme spread of 79 fps, the other 85 fps, I'm used to seeing less than half that at 100 yards with the pellets I normally use.  Highs at 710 fps+ and lows at 630fps- So I pull out the old trusty ruger 10/22 and shoot a 10 shot string, which was exactly as it always is, so no chrony problem.  Moved chrony to about 2.5 feet and fired a 10 shot string with the JSB's and had a nice 5 fps extreme spread averaging 891 fps, so I shot a 20 shot string and it had a 9 fps extreme spread (typical with my cricket 7-9 es on 10 shot strings at the muzzle). hmmm.  Added a bit of air and shot another 10 shot string with the JSB's at 100 yards, 75 fps extreme spread.  While I wasn't exactly target shooting through the chrony I got a good enough feel for them, had a board behind chrony for aimpoint, and I know both varieties of the H&N pellets I've been using are more accurate out of my rifle than the JSB's at distance.  Apparently the JSB's have a problem going longish range out of my rifle.  Guess I'm stuck with a lot of short range plinking and pest pellets now I guess. 

[triggertreat]

Are these the standards or the MKIIs? 

[LDP]

My Daystate wolverine shoots the JSB MK2 pretty bad also. I have single loaded them and they just dont group out of my wolverine. They are only going about 790 fps so maybe kicking the velocity up to 860+ might help but I have not tried it.

[rsterne]

My Hatsan AT-44 Long loves the 34 gr. Mk IIs at 930-960 fps.... Just over 1" groups at 100 yards.... Tethered I shot them over the Chrony, 9 shot averages were 915 fps at 1 yd. and 688 fps at 100 yds.... similar ES at both distances, about 1.5%.... That is a BC of about 0.048, I was quite pleased with that.... They sure lay the smack-down on a Marmot at that range....

Bob

[LDP]

My Hatsan AT-44 Long loves the 34 gr. Mk IIs at 930-960 fps.... Just over 1" groups at 100 yards.... Tethered I shot them over the Chrony, 915 fps at 1 yd. and 688 fps at 100 yds.... That is a BC of about 0.048, I was quite pleased with that.... They sure lay the smack-down on a Marmot at that range....

Bob

Bob I have seen many posts from people having good luck in accuracy with the heavies up to 960 or so fps but I also seen many posts with people having just as good luck at 770 - 800 fps that some pcp push these to. I just dont know if its going to make any difference pushing them faster from my wolverine. I figured they would shoot at least as good as the kings even if they are below 800 fps but not even close. I would hate to up the power just to see no improvement but I guess I will never know unless I try

[Wayne52]

The MKII's work fantastic through the Green Mountain barrel on my Mrod, that reminds me I need some more I'm getting low.  I still have an ample supply of the the H&Ns both grizzlies and domed and they also shoot great in my gun.

[KarlH]

Are these the standards or the MKIIs?

They are the MKII's. 

I just shot a good group with them, estimated yardage 30, just a quick set to see if I was going to take the time to do long range test of accuracy.  I really think long range with them is a waste of time having such an extreme velocity spread at 100 yards.  I ran some numbers starting with 892 fps muzzle velocity of my setup and varied ballistic coefficient to match high and low velocities I got at 100 yards.  This results in just over 2 inches of drop difference, so that is where accuracy starts with these pellets and my rifle at 100 yards with everything else perfect, which of course is impossible.  I have two pellets I can use now that I shoot just under 2 inch groups at 100  yards all day as a worse group, not best or average group.

Something is going on with JSB's to have such a tight velocity spread at the muzzle and scaring 100 fps spread difference at 100 yards.  I was going to shoot some at 100 yards somewhat seriously this morning but the biting insects are out in force and chased me back in the house.  And I'm not going to do any semi-serious shooting in the mid 90's heat and over 50% humidity today and the rest of the week.  Early morning before sun is over the trees is only time it's comfortable enough, the air is thick enough to cut with a knife.  I feel like I sweated out 5lbs of water  yesterday afternoon messing with the chrono.

[KarlH]

Got out the spray tank for the tractor and mixed up some permethrin, sprayed my deck and several hundred square feet of the yard around the deck.  That took care of the insects when the sun was down.  With the lay of the land from the deck I had to move my target back to 113 yards to clear my line of sight.  So, with my truck down range and headlights on target, I proceeded to shoot 4 10 round very careful groups a couple hours after sunset, dead calm conditions.  All 4 targets were identical, and all 40 rounds broke clean and pure.  Each group had 6 rounds tightly clustered, largest group of 6 was 1.2 inches, smallest was 0.8 inches.  3 of the four targets had one round .5-.75 inches out of the tight 6 round cluster, the fourth target had one that was about inch out.  The other 3 rounds on each target were randomly all over the place making all 4 targets having over a 3.5 inch group.  After thinking about it, I took the orings out of the magazine and looked carefully with my reading glasses.  There were 3 holes that had the smallest tiniest bit of lead shine smaller than size of a period made with a ball point pen on the leading edge of the inner ring where the orings go on the magazine.  There was one hole that had an even smaller shiny spot on the outside leading edge of a hole.  Kind of adds up with the targets I shot.  I pushed some pellets through clean holes and the 3 with the inner mark using a punch and the pellets really barely had any kind of mark on them out of the 3 "problem" holes and were perfect out of the others. It was really just a shiny spot, not a gouge/scratch/dent/ding just shiny and tiny.  Pellets were perfectly clean pushing out of the other holes.   I'm sure the pellet probe does not push the pellets out as straight as I did with a punch that fills the cavity of the pellet and pushing perfectly straight and easy.   Don't have time this morning, but this evening I'm going to try to shoot some groups single loading without the magazine.  May have found the culprit, strange it doesn't do that with the two pellets I normally use.  If I get around to shooting single loaded tonight I'll post an update.

[triggertreat]

Good to see you are having some good luck with the MKII's.  I have been testing them out too after ordering 8 tins of them.  I have been getting 1/2" groups at 50 yards shooting them anywhere from 50 FPE to 55 FPE depending on my tunes.  They sure do pack a punch which I like.

[ackuric]

Magazines are notorious for causing pellet damage from cycling or from burrs inside the magazine itself!
If I am shooting 100+ yards for groups I would prefer to single load by hand after examining the pellets skirt + head for deformities.

When testing the BC on these pellets I tested around 4 clips worth (32 shots)...not sure if Bob achieved an average of .048 in similar fashion or shot just a small group or what, but he must have very amazing tuning skills to get absolutely zero variation from shot to shot  ....My average BC from 24+ shots was .046

There is quite a change in BC from pellet to pellet, so its best to obtain an average over a large group.

-Matt

[LDP]

I just upped the power of my wolverine to shoot the mk 2 around 870 fps. Im heading out to shoot for groups I will post later or tomorrow with my results.

[K.O.]

wow Matt ... casting aspersions on Bob... are you implying that he is lying...the ax you are grinding is making things a bit less pleasant around here at least for me...

He  stated 1" groups which takes a very well tuned rifle with a very tight es... at the minimum of a 2% es at the muzzle... but also takes making sure your barrel is up to snuff... if you are having  quite a bit of variation of B.C. from pellet to pellet and your MV is tight you might want to  look there...

Bob  has a different theory than I about how Lloyd's hyper-gun achieved over  2000 fps...and I felt he did not give my theory much credence... but  because its is by nature difficult form me to really communicate my theory well... I have some concentration probs (bad at times)...Point is I did not take it personal... I still think his theory may be wrong because it relies on a pseudo closed system not seeking balance and all systems seek balance...

We all seek affirmation and sometimes get defensive when it is actually not needed... I think you are an intelligent guy so just try to relax  there really are no top dogs here other than the mods...So relax a bit I think you have a lot to offer to the gestalt of what this place can be...

Besides a nut house that is..

I am just saying tone matters...

[LDP]

Well I found out something interesting about my wolverine. Probably not interesting because every pcp reacts the same way but it is a little different from what I have seen others experience. So yesterday the wife and some friends wanted to head out to the lake to get away from the heat so they swam and played in the lake while I tuned and shot the wolverine in the woods

  When I received my wolverine it was shooting Kings at 900 fps avg. and King heavy mk2 at 800 fps for an average. I would get good groups from the kings but with one or two flyers that would open the group up from one hole. The accuracy from the king heavies was disappointing so I sat them aside and decided that the kings at 900 fps would be fine. The one or two flyers out of every group with the kings was bothering me so I spent the last few weeks looking at different things to try and stop it. I was reviewing one of my scope cam shots when I seen what was happening. I could clearly see the pellet spiral in the video but they were not spiraling every shot. I then started to shoot the pressure down in the tank until the velocity started to hit 880 fps and lower. The flyers started to go away the closer I got to 860 fps.

So armed with that info I decided to try two things yesterday. First I was going to raise the king heavy velocity up until it maxed out to see if they would group better when shot faster. Second I was going to shoot the kings faster to see how the groups would change and see if velocity increased over 900 fps would make them open up even more.

I got the king heavies up to 835 fps avg and thats as fast as the wolverine would push them. The groups were very good and I shot multiple groups just to be sure. There was a good breeze during some shots that pushed a couple pellets. I wasnt in a great spot for precise shooting but the groups were still very good.

Then I kept the settings the same and started to shoot the kings. With the wolverine maxed out the kings were getting pushed to 930 fps. I only shot one group and it was not good at all. The group didnt have any pellets clustered and they were just scattered with only two touching. So I believe at the faster velocity the kings were spiraling every shot. The wind was calm on this group and it was probably the only group that I felt solid every shot so I dont believe anything but speed played a role in the groups size.

So my wolverine does not shoot JSB pellets at its best if velocity is 810 fps or lower or 870 fps or higher. If I get outside those velocity numbers groups open up. I dont know what causes the issue at the lower velocity but at higher velocity I start to see spiraling pellets. I dont know why they start to spiral above 870 fps either. Not sure if its the barrel, hugget ldc or something else with harmonics.

These pics show the king heavy mk 2 groups. Everything was shot at 50 yds.

The hit to the left was the very first shot from the wolverine of the day. I shot 5 more and they all went into that small cluster. Not sure why the first one hit to the side if it was wind, me, pellet or just nothing   Shot at 50yds


Group covered by a nickel. I believe the cluster could have been covered by a dime.


This is the third group from the king heavies. This is a 20 shot group and for me tells the whole story and shows the accuracy potential of the king heavy mk2 with the correct velocity for the rifle. Theres one shot just pulled right but this group wasnt shot slowly and it could have easily been the wind or me. Shot at 50 yds.


Same group covered with a nickel.

[mann]

From what I've seen and read the sweet spot for jsb heavies and jsb Kings seems to be right around the 850 fps Mark that's the way my .25 marauder is also

[KarlH]

... when I seen what was happening. I could clearly see the pellet spiral in the video but they were not spiraling every shot. I then started to shoot the pressure down in the tank until the velocity started to hit 880 fps and lower. The flyers started to go away the closer I got to 860 fps.

...
The hit to the left was the very first shot from the wolverine of the day. I shot 5 more and they all went into that small cluster. Not sure why the first one hit to the side if it was wind, me, pellet or just nothing ..

Every diablo pellet I have ever shot out of my cricket that is less than 30 grains spirals regularly.  I'm well over 900fps at that low of a pellet weight.

As for the first shot of the day, my cricket has done that often enough that when I pick it up to shoot a pest(s) , I'll send one to the back of my 17 acres first if I have shot the rifle in the previous day or two.  It won't always do it, seems like it does that more when it has been only a day or two since it has been shot, but if it's been a week or more it doesn't do that with the first shot of the day(most of the time).  It won't do it all the time, but often enough that it is a pattern I have recognized.

I tried to shoot a bit last night after dark, but I could not hold well/concentrate good enough.  Too tired, long day, and age catching up.  It's a shame to since I had a long thunderstorm that knocked the temp down from 95 to the low 70's just before dark.  I single loaded 10 of the 34 grain jsb's, and they did not do well.  Could have been me though, I was just not shooting well and decided not to waste any more time last night.  I get the feeling that it is still throwing out several in 10 shots randomly and may not be a magazine issue, might be random spiralling of pellets.  I won't swear to it since I know I was not capable of shooting well last night.  I'll get to it in the next few days when I know it's the pellets and not me if it continues acting like that. 

I won't be turning down the power of my rifle to shoot the heavy jsb's if that is what it would take, my cricket shoots two of the H&N heavier pellets well at the power it is at now, and both do clean pass throughs on coyotes at just over 100 yards.  I know I'll catch heck for that, but since the coyotes came in force the last few years, I never see flocks of turkeys on my land anymore and i've gone from seeing a dozen or more deer every week to seeing 1 every other month.  Coyotes aren't native to here, they are destructive, and I don't care how I kill them or how anyone else kills them, just so long as they are getting killed.  If I get a shot of opportunity out front, it is the air rifle at around 115 yards where they cross a bench between me and my neighbor.  My neighbors house is another 170 yards past that off at a bit of an angle, with another 15 feet of rise on his land and then at least that much down from the crest on his land before you get to his house.   I won't fire a real rifle in that direction just to kill a stinking coyote cleanly.  But I very happily put a .25 pellet clean through it's lungs when I get the chance, the count is up to five so far, love hearing that thump. 

[KarlH]

Well, It's official.  My cricket shooting an average 892 fps at the muzzle with the jsb king heavy 33.95 grain pellets just won't shoot worth a "dang".  I shot another set of 5 10 shot groupse single loading without the magazine in perfect conditions and the best was 3.5 inches at 113 yards.  Excluding one ridiculous flyer the worst of the 5 was just about 4.75 inches, with the ridiculous flyer on the one group it was 14 inches.  I saw that one spiralling in the scope.  Sunlight was just clearing the trees behind me and put a good shine on that spiral.  In between those 10 shot groups, I shot one 10 shot group with the H&N grizzlies and got the best group I have ever had with them, sheer randomness of course as all best groups are with any type of weapon, at 1.25 inches at 113 yards(realistically they have averaged 1.5 inches at 100 yards for me after sorting).  It's not the air rifle, it's not me, it's not the wind, the jsb heavies just won't shoot out of my cricket at the power level I choose to shoot at. 

Anyone live around York or Rock Hill SC or Charlotte NC?

[grand-galop]

wow Matt ... casting aspersions on Bob... are you implying that he is lying...the ax you are grinding is making things a bit less pleasant around here at least for me...

He  stated 1" groups which takes a very well tuned rifle with a very tight es... at the minimum of a 2% es at the muzzle... but also takes making sure your barrel is up to snuff... if you are having  quite a bit of variation of B.C. from pellet to pellet and your MV is tight you might want to  look there...

Bob  has a different theory than I about how Lloyd's hyper-gun achieved over  2000 fps...and I felt he did not give my theory much credence... but  because its is by nature difficult form me to really communicate my theory well... I have some concentration probs (bad at times)...Point is I did not take it personal... I still think his theory may be wrong because it relies on a pseudo closed system not seeking balance and all systems seek balance...

We all seek affirmation and sometimes get defensive when it is actually not needed... I think you are an intelligent guy so just try to relax  there really are no top dogs here other than the mods...So relax a bit I think you have a lot to offer to the gestalt of what this place can be...

Besides a nut house that is..

I am just saying tone matters...

Well Kirby!!  I have to SALUTE your diplomatic statement and that was my assertion last time we cross talk together... I`m definitely with you on this and we can make BIG THINGS here if we let our EGO at the door... With all the great minds here, we will find all the answers to ANY PROBLEM...  Thanks man!!

[rsterne]

Likely too fast a twist rate to work at that velocity.... If you saw spiralling in even one shot, it was likely present in the others, you just weren't noticing it.... If the rifle shoots well at 50 yards and the groups open up after that, you can almost 100% blame spiralling, IMO.... which means Dynamic Instability.... which generally means too fast a twist for the velocity.... The fact that you are seeing large velocity swings at 100 yards that are absent at the muzzle also indicates to me that the pellets are "wobbling" (nutation and precession) as they go downrange, a sign of Dynamic Instabiliity, which leads to spiraling.... Not that you can do anything about it (short of a new barrel).... but do you know the twist rate in the Cricket?.... That info could add to the body of knowledge about the 34 gr. JSBs as to what works and what doesn't, and more importantly why...

Bob

[KarlH]

Likely too fast a twist rate to work at that velocity.... If you saw spiralling in even one shot, it was likely present in the others, you just weren't noticing it.... If the rifle shoots well at 50 yards and the groups open up after that, you can almost 100% blame spiralling, IMO.... which means Dynamic Instability.... which generally means too fast a twist for the velocity.... The fact that you are seeing large velocity swings at 100 yards that are absent at the muzzle also indicates to me that the pellets are "wobbling" (nutation and precession) as they go downrange, a sign of Dynamic Instabiliity, which leads to spiraling.... Not that you can do anything about it (short of a new barrel).... but do you know the twist rate in the Cricket?.... That info could add to the body of knowledge about the 34 gr. JSBs as to what works and what doesn't, and more importantly why...

Bob

I can get a rough estimate of the twist rate with a cleaning rod, but that may not be the answer.  From decades and 100's of thousands of rounds through powder burners, twist rate is not always the answer on stability issues with a particular round and velocity, seen many rifles with the same twist rate not able to stabilize one loaded round, but other rifles with same twist rate and exact same round (sometimes even the same manufacturer match barrel) have no problem, even going to heavier bullets.  There is a lot of variablity even in match grade barrels whether cut/button rifled/or hammer forged.  About a decade ago a friend that shoots unlimited class 1000 yard(I call them artillery pieces, not rifles) went through 5 krieger barrels on a build before he got one that worked, all 5 exact same specs and nowhere near the edge of what should have worked on twist rate.  Some barrels are just more picky than others, he ran into an extreme example.  I was with him when he was fire forming cases on the 5th barrel playing with his old small bore 100 yard rifle while he shot the artillery piece at 300 yards just fireforming cases for it.  He said the barrel was showing promise.  I looked through the spotting scope and all I saw on his target was one slightly large hole so I had to ask if fireforming cases does this what could possibly be wrong with it.  Apparently two of his failed barrels didn't start breaking down accuracy until past 700 yards.  I think its magic or voodoo, makes no sense to me.

[K.O.]

Me I would like to see a thread of leade pics of all the different barrels of the stock rifles here... the further out you go the more important the small things become and the leade is one of those areas that seems to be ignored...

Bob makes his own chamber reamers with a low angle leade I think he and others suggest 1* is best... point is  Maybe the leade on many of the barrels  are not up to snuff... I know that My Mrod .25 green mountain barrels are not... they work great out to 50 yards tho... well one hated the Benji domes until I did some leade work then they improved quite a bit... It now likes them better than the other .25 Mrod that tolerated them that I have not worked on...

all it takes imo is a small amount of damage to the skirt or not feeding into the rifling straight to help induce dynamic instability at long range...

The further we want accuracy at the more gremlins there are to chase...

Then there are also barrel harmonics the more fpe you push the more likely they become and the further you are shooting the more even small amounts matter...

It is only in recent times that the availability of the higher weight /sd/bc pellets have become available that help allow longer shots to be more feasible... I am betting many of the Manufacturers have not caught on to the importance of a good leade yet... I know Crosman/Benji has not yet... pics below... No leade just sharp edged rifling... and from what I have read the extra heavies would possibly be sensitive to that... I have not tried them yet... I went for the BBT 40g which definitely need a proper lead...

think about .22lr at 100 yards a match chamber is needed for reliable accuracy.