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Cricket velocity spread problem

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This topic contains 25 replies, has 5 voices, and was last updated by  MikeGB 1 day, 22 hours ago.

Viewing 11 posts - 16 through 26 (of 26 total)
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  • #526996

    MikeGB
    Participant

    That’s interesting, thanks for the info.
    I am still waiting for a selection of O rings to arrive to, hopefully cure the leak from the cylinder end, I got some 16 x 2 but they did not stop it entirely.

    #527152

    gku
    Participant

    I’d go with the 85 bar reg settings …….
    Play around with the Valve and Hammer spring tension to achieve a balance of the 2.
    Try setting valve spring tension to 3-4 turns CW too.

    I’m not usually into 12 f/lbs tuning so my knowledge is rather limited.
    I’d check into some UK forum if u haven’t already ……..

    ……. also the tissue test u did on the underside could have come from the turbulence caused by the hammer making it’s way onto striking the valve ?

    ~ Greg

    • This reply was modified 2 weeks, 6 days ago by  gku.
    #527201

    gku
    Participant

    Also Lane is a great resource for regulator theory.

    You need to do a full shot string and study its curve ……..

    • This reply was modified 2 weeks, 6 days ago by  gku.
    • This reply was modified 2 weeks, 6 days ago by  gku.
    #527278

    MikeGB
    Participant

    Will give the settings a try.

    Posted questions on some UK forums but haven’t got anything useful off them, several suggestions of sending it to the UK importer but I have found them very vague or unhelpful when I have tried contacting them.

    Not sure if I am on the right track but tried sealing the hammer area and under the trigger mechanism opening in kitchen film and put the tissue under the trigger rod and it is still moving a bit with the 16 x 2 O rings on the air cylinder.

    I’m not a big fan of videos for technical stuff, I like something that I can to refer back to particular sections easily, I have downloaded a lot of the Lane documents since I got one of their regs and have done the tests in the ‘mini service guide’ a number of times and the 45 second test curves are improving but still a bit uneven, they did offer to take it back for testing but the Huma reg is producing similar results after it was tested so thought it probably wasn’t the regulator.

    #529444

    kris
    Participant

    Man you have to turn the barrel so it clips the flow path, that way you can add more hammer spring tension. While you keep it around 575fps.
    That way you can keep the high reg setting.

    Don’t lower the reg too much that would make the gun inefficient and loud. Instead try what I suggested.

    120-130 is high I would go to 90 as you will not have dead air just sitting in the cylinder what you never shoot. But don’t go too low as it will hammer bounce and waste air without making power.

    Setup the TP and hst at low fill not with full cylinder. Only if you are happy then refill and verify fps with full cylinder. Will take a few turns but can be done.

    Watch out for unbalanced effects as such: different power at or under the reg setting versus full cylinder. A properly setup gun has low extreme spread over the wide fill range and at the same time low shot to shot variation.

    • This reply was modified 1 week, 2 days ago by  kris.
    • This reply was modified 1 week, 2 days ago by  kris.
    #529513

    MikeGB
    Participant

    I’m still working through a lot of the suggestions, changes to the hammer spring seem to give changes more than other things, I have had it running at 900+ fps and only showing a 20 fps spread on some shot strings but as soon as I turn it down it all goes away.
    I tried a 40 mm hammer spring of 1.0 mm dia wire and even with the main valve spring retainer only in half a turn and the adjuster full-in the hammer still wouldn’t open the main valve much. Found some more info on hammer springs about how the ends are important as it can alter position between shots so altering how the hammer hits, am currently getting better results with a 50 mm spring, 1.2 mm wire with ends ground square and polished. The original spring it had in really looked like it had been butchered and I am told it is the UK importer that leaves them like that.
    Have also had a suggestion of putting a small plastic sleeve round the hammer spring as it was thought it could catch on things if the spring distorted at all.
    Will try turning the barrel etc., thanks for the suggestions.

    #529515

    MikeGB
    Participant

    It would seem to be the hammer spring that is the cause of most of my problems, the 1.2 mm wire size one was an improvement, then tried a 50 x 9 x 1.4, paid a lot of attention to squaring the ends and polishing it, plus how it was seating in the hammer and adjuster and am down to single figure fps spreads most of the time now.
    Think it is just some fine tuning needed to match regulator settings and stuff and will try turning the barrel as it is border-line for legal here with the adjuster fully out.

    Many thanks for everyone’s ideas and suggestions.

    #529517

    kris
    Participant

    So what is the power at 80bar left in the cylinder with your current hammer spring, if your hammer is shortened or weaker wire power will trend up to impressing numbers if you are not careful setting up the TP.

    Also I read somewhere that some shops filled the plenum on some guns with some delrim bits in an attempt to reduce volume/power but failed miserably so I would check that making sure your valve and the plenum is normal, then adjust the TP.

    If your reg is set that high 130 you have to clip the transferport a lot to even it out. The FPS will depend a lot on cylinder pressure regulated or not. Choke it down. Usually helps

    • This reply was modified 1 week ago by  kris.
    • This reply was modified 1 week ago by  kris.
    • This reply was modified 1 week ago by  kris.
    #529523

    MikeGB
    Participant

    I haven’t tried letting the cylinder get down that low yet, still experimenting with rotating barrel, friend says the transfer port is only about 1.0 mm dia in his 12 ft/lb FX Dominator, it has a brass restrictor in, leaves about a 4.0 mm dia hole if it is removed, wondering if I could do something like that between the air cylinder and barrel.
    Also read about starting full in then backing the hammer spring off to see if there is a ‘sweet-spot’ power increase at any point and been trying that at the same time as barrel rotation.
    I have had most of it dismantled and not found anything that doesn’t look like it belongs there, not sure if the main valve is standard.
    I am finding it very slow to fill after I changed the O rings, backed the screw in the fill valve off a little, twice but it’s not making any difference.

    #529708

    kris
    Participant

    How is it going?

    #529709

    MikeGB
    Participant

    I think it is about sorted, thanks for asking.
    The velocity spread problem is fixed, still experimenting with hammer springs and port size from air cylinder to barrel a bit but am a lot happier with it now.

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