What a difference 0.01 mm makes.

Discussion in 'Hunter (HFT) & Field Target (FT)' started by peterh, Aug 8, 2013.

  1. peterh

    peterh Stoopit forriner.

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    I've been backyard-plinking a bit tonight... with results that, at least to me, are hugely instructive.

    Management summary:
    1. I can still shoot half-decent, at least when sitting, so apparently, one doesn't completely forget how to shoot in 10 years.
    2. an Air Arms 100 that shoots surprisingly well with 4.51 pellets, goes completely to pot with 4.52 pellets of the same brand and type.

    More information and group pictures at http://peterhuppertz.net/blog/blog/2013/08/08/a-hundredth-of-a-millimeter/

    (Yes, I know. I could have put it here as well, but then I'd have to type it twice, as I also want this to appear on a Dutch forum. You benefit from the fact that the writeup is in English.) ;)
     
    Last edited: Aug 8, 2013
  2. burjaka

    burjaka Member

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    Your passion is still very strong.
    Welcome back.
     
  3. rich

    rich Active Member

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    My EV2 is like that. Any pellet that is reasonably loose in the breech, seems to fly OK. Get one that is a bit tight and where it finishes up is a lesson in random behaviour.
     
  4. RobF

    RobF Administrator Staff Member

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    There's a prize for anyone who can measure 4.52 on a pellet ;)

    Chances are 4.53 would go just as we'll as 4.51. The sticker on the tin may as well say 8.53 for all it does.

    Just batch variation.
     
  5. TOOL

    TOOL Independent FT Pumper

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    Jesus H Christ now I've heard it all !!!

    I've heard some excuses but this is a first !
    If you honestly can see that 00.01mm of tolerance in a lead pellet landing you must be one hell of a shot and get yourself to Worlds and every other competition major or other wise to mop up the prizes !

    Just found this on YouTube explaining tolerance differences causing indifferent flight patterns

    Interesting http://youtu.be/4pQcn2L65J0

    Maybe it could be you ................. ?

    Ever acctually thought of that one ............?
     
  6. rich

    rich Active Member

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    Why do you think it's an excuse?

    I've owned my EV2 since October 2004 and tried it with pretty well every make of pellet that is on the market. After thousands of rounds, the consistent picture that emerges is that tight fit pellets do not group as well as looser fit. Whether that is due to deformation as they are seated by the probe, or details of the barrel choke, I don't know, and frankly does that matter?

    Regarding the stated size of pellet, that is a red herring. One of the best pellets in this rifle is the JSB Exact Express and on the tin it says 4.52. One of the worst is the Bisley Magnum. Every one of those feels tight on loading.

    After nine years I think I have a reasonable grasp of how this gun shoots.

    My trophy cabinet only has one BFTA goblet as I don't take part in the national scene in FT. :p
     
  7. AIRFIX GILLY

    AIRFIX GILLY WFTA World Champion 2012

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    makes all the difference

    0.01mm makes all the difference to me!

    Since I've started having a grade 3 blade on top instead of a grade 2 I've managed to win several height offs recently.

    My last win was over Chloe at my local club who I beat very easily.:)
     
  8. peterh

    peterh Stoopit forriner.

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    Keep yer shirt on, Tool. No reason to get all wired up about it. And if you'd take the trouble to look at the groups, you'll also see that my shooting abilities, even with windless conditions, are not of the sort that justifies prize mopping on a Worlds. I'm improving, but not nearly as good as I used to be... and even then I wasn't at Worlds prize mopping level.

    Yes, I have been thinking long and hard about how the shooter's peace of mind can contribute to a result. And it's not the first time - I am convinced that I'd be shooting a lot better if the bottom of the tin would say 4.51 than if it would say 4.52, even if the same pellets were in the tin.

    This explanation, however, does not cover why I was shooting groups the size of a 10 pound note all of a sudden, because I was not aware I was shooting with a different pellet. I was seriously worried my rifle had broken, and was already contemplating getting the chrony out.

    While I agree that pellet selection is a dark art, a substantial part of which is probably in the mind, and it is hard to see how 0,01mm could make a difference, what I saw in the past, and what I am seeing again, is that a rifle that shoots quite well with one pellet, goes completely to pot with another. The funny bit being that there was seemingly no single reason for it going to pot, not even a reason that could be explained psychologically - if I would have known that I was using 4.52, that might have explained it, but I was not aware of that.

    Yesterday's practice session was, of course, not even close to a controlled experiment. The only reason why I went back and picked up the correct tin was to see if I could end the practice session on a somewhat less depressing note, because I was seriously worried.

    So, this morning in the car, I thought of an interesting experiment. Person A (not being me) takes two identical (new) tins, a 4.51 and a 4.52. The stickers are removed, and the tins are marked in a way that does not suggest a particular order (say, an O and a zero), so that person A knows which is which and person B (being me) has no idea whatsoever.
    Person B (being me) then sits down and shoots groups from both tins. What will they look like?

    Since I have no access to an indoor range, this experiment can only be performed when the conditions are right, enough time is at hand and the stars are properly aligned. But I will probably do it in the near future; curiosity has got the better of me.
    If anyone has any other suggestions for things I might want to try, please please pretty please with a cherry on top let me know.

    Having said all that, how do YOU (without throwing a tantrum spiced with exclamation marks, please) explain the unacceptable group sizes in the first picture, keeping in mind that I had no idea that I was shooting with the wrong pellets?

    @RobF:
    You and I may not be capable of manually measuring a pellet's diameter, but trust me... manufacturing and automated tolerance control has gotten to a point where a proper plant can actually do it without having to resort to black magic. In camera manufacturing (and doubtlessly a lot of other branches of manufacturing as well), tolerances are expressed in single micrometers, so 10 micrometers shouldn't really be a problem.

    Batch variation would be a better explanation.
    Another might be die variation.
    I'm not sure how this works... I'll see if I can do some research. But if the various sizes come from different dies... if they do, we may have discovered another variable that might play a role in pellet performance. I remember that Crosman used to mark on the box which die number their Premiers came from.

    Lemme see if I can find out a bit more about this.

    To put this in perspective, there IS a story (I got it from Nick when we were staying with him in 2001, so it's fairly old) that illustrates how faulty shooting is usually a short between the earphones.

     
    Last edited: Aug 9, 2013
  9. rich

    rich Active Member

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    Ever tried shooting bench rest, Tool? It's a lot tougher than FT to score well. A millimetre off line at 20 yards can mean a 9 not a 10, and you don't get anywhere with a card with many 9s on it.

    Bench rest is really pressing the envelope when it comes to the consistency of the pellets.
     
  10. NJR 100

    NJR 100 Because I`m AWESIME !!

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    I loike it when tool takes his shirt off, it keeps me amused for hours reading tatoos.
    One day i am going to have a tatoo done, of an Ev2 :)

    Anyway, 4.51,52,53 = waste of time. Myth. Pellet will be closeer to 4.46 -48 on head.

    Its the die number that counts.
    I could say go and read my findings in how do you miss, but I dont think your that young.
    Today is another pellet testing day at tondu, if the wind is up might launch the new pellet testing lane.
    I baught 9 different tins of jsb the other week from intersoot. We have been testing them in different guns to see who's gun works with what. Each of us is heading to different results
    Gadget = die 34
    Zak - Die 11
    Shunter - Die 8
    Me ? ? Well Rev likes die 34,but i need another confirmation day:D
    No dark art, papar targets at 40 + 50m, 10 shot groups. Two groups, get up, refresh, start over.
    40 m even Gadget can group almost pellet on pellet at times, and that with his hands. 50 m is where it will show whats really working well!

    One thing I never noticed with my ev2 is tight and slack fitting pellets. Maybe something different betwen mk 1 and 4 Ev? Maybe i just never took notice?
     
  11. peterh

    peterh Stoopit forriner.

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    LOL! ROFLPMP!

    I wasn't aware that JSB puts the die numbers on their tins... from the tins of JSB that I still have, the sticker on the bottom has faded completely. Similarly so on my tins of AA Field - only the stickers on the bottom of the Daystates are still readable.

    Anyway... looks like the number of dies is higher than I'm ready to test - I can't see myself buying 32 different tins of pellets ;) (hopefully they don't have 34 dies and I can get by by getting just a couple tins.

    I'll see if I can break a left arm or something... that would allow me to get some free time to read through the How To Miss threads.
     
  12. RobF

    RobF Administrator Staff Member

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    I actually can. About 5 years ago I got a block made with 4.53 - 4.48 holes put in it. Offer up 90% of pellets from any JSB tin and their heads will slip into the 4.50 hole. The tails are too random in size and shape to measure.
    That's why I know head size as stated on the tin is just a sticker. As Simon says its the batch that counts.
     
  13. TOOL

    TOOL Independent FT Pumper

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    Never tried bench rest, does it involve a key board ? or a laptop ?

    Because all these Pilchards that spout about accuracy this accuracy that can't actually shoot for sh1t that's what they seem to hide behind ?

    My advice would be if your shooting FT and I can only speak about FT is .................

    1. Find a reliable cannon
    2. Find some really good bullets that match / suit your barrel
    3. Take tape of the tin
    4. Shoot the f@ckers !!!!!

    TTFN
     
  14. Conor

    Conor Never been banned from sales Staff Member

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    Scott my dear friend I need a quiet word in your ear...you do appear to be drinking excessive amounts of caffeine at night, surely we don't have keyboard shooters on a highly regarded and respected forum dedicated to outdoor target shooting with air rifles! Even the coppers are logging in apparently.
     
  15. Jon

    Jon Member

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    Still sizing em 4.47 Rob, anything else don't touch the heads in most batches.
    Been saying for years in fact most producers inc H&N are the same and don't measure whats on the tin. Not been using JSB that long but only ever come across three batches that measure whats stated on the tin, first was from 2002.
    Lets just say manufacturers know when they've made a good batch!

    The die may start out a certain size but in high demands I reckon the multiple dies going in to each tin (unconfirmed) are sped up. You should all know what temp does to dimensions.
    Its not only the head diameter that's out the lengths can be different as well approaching 0.5mm.

    By the way best groups ever repeatedly seen were with Maggies when they did measure 4.52.
     
  16. peterh

    peterh Stoopit forriner.

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    [...]
    5. Observe how the manufacturer will discontinue them bullets, or will change dies, and you're back to square 1. :eek:o

    ;)

    Caveat: I'm not claiming I am as good as you are. What I see is that, all of a sudden, my shooting falls apart... then I get a different tin and I'm back at sub-pound-coin group sizes again. Never too old to learn why that is.
     
  17. TOOL

    TOOL Independent FT Pumper

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    Really ? the rozzers are looking at me ? OMG :eek:

    Think we have been down this route before .......

    I spoke to my neighbour last night who is a senior police officer & he quoted this http://www.youtube.com/watch?v=cgqDvrAgktg

    Then this
    http://www.youtube.com/watch?v=4pQcn2L65J0

    Stopped drinking coffee when my left plum started to swell up mate.

    If anyone does have any formal complaints about me quoting / writing jibberish on here the please phone the Plod on 999
     
  18. mr dink

    mr dink Member

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    I started to :bic: them when i got my first PT 98 i think, and the pellets would stop at different point,s down the tube then some years later they all started to fall through the same bic and still do so as Rob say,s it,s just a sticker.
     
  19. peterh

    peterh Stoopit forriner.

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    ... which would basically indicate that, when you are trying to 'find the right pellet', you are still at the mercy of the Gods. You find a good one, and then the manufacturer botches it.

    This would mean that, when you find 'the right pellet', you should buy as many tins of that particular batch as you can find, and then live off that for some time... and then the entire process starts from scratch?

    That would actually make sense...
     
  20. willo

    willo Nikon Shooter

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    Scott can be seen checking the size of his pellets with his micrometer fingers as he inserts them


    <a href="http://www.flickr.com/photos/54252691@N06/9231934321/" title="DSC_1539 by willo_wisp, on Flickr"><img src="http://farm4.staticflickr.com/3762/9231934321_de4bf267d0.jpg" width="500" height="332" alt="DSC_1539"></a>


    :D
     

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