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Thread: Pellet Air Gauging on a shoestring...

  1. #1
    Sharp Shooter
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    Default Pellet Air Gauging on a shoestring...

    I decided to whip up an air gauge for pellets this morning. With a bit of creativity and some hardware bits and pieces, easily done.
    Air gauging has been around since the 30's and is extremely accurate and consistent. It's also easy...no magic involved, just basic physics involving air back pressure.

    Make up a master sizer like below, set it up in the air gauge and start gauging.





    i have some videos of it in operation. Works like a charm. Sizing pellets is quick and easy.

    Last edited by Dallas; 23-09-18 at 02:33.
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  2. #2
    Sharp Shooter
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    I couldn't find a more sensitive gauge today, I'll get one next week...something around 0-2 bar is plenty...I'm sure RS Components will have something suitable.

    or you can use a digital pressure transducer with Arduino and some simple code.
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  3. #3
    Sharp Shooter
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    qe?........
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  4. #4
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    Super cool!!
    I've done the whole air gauging thing here at a friends house about a year ago but I only did like 1 tin of pellets and I couldn't properly test which variance my gun liked best!

    This seems simple enough for me to figure out though so maybe it's time to make my own.
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  5. #5
    Sharp Shooter

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    Just confirming the principle here .....
    - Set up a constant flow of air with a pressure measuring device that exhausts through an orifice a little larger than a pellet.
    - lower over a series of pellets and measure pressure increase with variations in the pressure being some function of the pellet diameter.
    - calibrate with a known 'reference pellet'
    ???

    If this is the case you can get very sensitive pressure readings at low air flowrates with a simple water manometer (inverted U tube of clear plastic tubing with food coloring in the water for visibility). I used one of these many times to balance twin SU carb setups.

    It also helps to have some sort of a spigot to mount the pellet on so that it is concentric to the sizing orifice.
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  6. #6
    Sharp Shooter
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    pretty much...there is a divet that the pellet sits in to keep the pellet centred in the nozzle...
    after a fair amount of gauging, i found that only the extremes made any real difference to my bench accuracy. So a small amount of "Smaller and Larger" sized pellets were removed leaving around 400 pellets which fall into 4 maybe 5 different size groups. These are then weighed to get rid of "extremes" in weight.

    These 4 or 5 sizes all scored 10's or X's....there was no discernible difference in POI @ 25m.

    You just have to weed out the "extremes"which in turn are the "Flyers". This is a lot quicker and more accurate using the Air Gauge than rolling and measuring. I can get through a couple of tins quite quickly.

    I have updated my gauge with a more sensitive gauge so it is easier to spot the differences. I have ordered the bit to make it digital as well. Will update the thread once i have done it.

    A word of warning, this device is extremely sensitive. The inside of the nozzle has to be perfect. Polished to a mirror finish and straight. Any imperfections inside the nozzle translate into big movements on the gauge. Ask me, i know....frustration.
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  7. #7
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    Just to be clear

    This whole exercise is done to ensure that all pellets are equal in diameter.?

    Which in adition to weighing the pellets will give an aditional improvement in accuracy due to air pressures being more constant behind pellet when shot.

    Has there been any testing regarding this as to the effect of such testing?
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  8. #8
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    Thanks Dallas your post came through while I was posting my lrevious one.



    Answer recieved
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