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Chrony Question

Discussion in 'Shooting Related Threads' started by willing, Nov 3, 2008.

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  1. willing

    willing Member

    Joined:
    Jan 29, 1998
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    Location:
    E NorthCarolina
    I have a Chrony and in using it
    ,it appears to read a little high. I shot a series of 5 shots each with factory 1145,1200 and 1235, averaged the results and found the readings to be around 5-6% high. I subtract 6% from reloads to determine their velocity. Is this the procedure to use or is there a method to calibrate the instrument.

    Bill
     
  2. shot410ga

    shot410ga Well-Known Member

    Joined:
    Jan 29, 1998
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    7,758
    Mine seems to be about 20fps higher than what's stated on the box or load. Maybe due to how far I stand from the device?
     
  3. BDodd

    BDodd TS Member

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    Oehler will tell you that any homeowner chronograph will have a need to reduce your readings with shot shells by 2 to 5%. Also long barrels and tight chokes will increase readings. My suggestion for simple use of your chronograph is to make tests with your gun, barrel, and favorite choke and start with a factory load you want to copy. Then make your reloads match (or more or less) the readings you got with your gun and your results with the factory load. In other words don't get hung up on what the box says the velocity is just use the chronograph to make reloads that copy factory loads with your gear.....breakemall....Bob Dodd
     
  4. g7777777

    g7777777 TS Supporters TS Supporters

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    I would call Chrony but frankly if it reads a certain velocity I would accept that- I would also weigh individual charges of the shells in question- you might find you have more powder or less shot than you thought

    regards from Iowa

    Gene
     
  5. Quack Shot

    Quack Shot Active Member

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    Mar 14, 2006
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    Im my obeservation, it appears that a more open choke will result in lower velocities. In general, the light screen based chronographs will read a little higher than the induction screen units that would be in use at a ballistics lab. As previously mentioned, firing a selection of factory shells will give you an idea what they provide regarding velovities and then you can use that as a guide to duplicate those velocities. I fond that I'm 25 fps or less away from the "estimated" velocies of the loads I have tried.

    In effect, the data you obtain from your chrony is more comparitive than and absolute reading. It is quite repeatable and consistent when done right, but the actual velocity can vary from your readings.
     
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