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Barrel length for load data

Discussion in 'Reloading' started by Trigger71, Feb 14, 2017.

  1. Trigger71

    Trigger71 Member

    Joined:
    Aug 9, 2016
    Messages:
    32
    Location:
    Grand Haven, MI
    Good Morning again!
    I was just reading an article about chrono'ing and shot velocities and it dawned on me that I didn't see any info on what barrel length was used in the manuals for fps. Anyone know, and if so is there a standard between all manuals?
     
  2. templetk!!!

    templetk!!! TS Member

    Joined:
    Jul 22, 2016
    Messages:
    21
    Location:
    Ohio
    On 02/09/2017 Precision Reloading, Inc. tested 28 gauge reloads for me using a pressure testing barrel length of 26 in. with a bore of .546 in.


    Ken
     
    Trigger71 thanked this.
  3. Ross

    Ross Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    2,837
    I "seem" to remember reading somewhere,,, 28" cyl bore, NOT sure.
     
  4. gregpete

    gregpete Active Member

    Joined:
    Mar 22, 2010
    Messages:
    332
    Distance from front of barrel to the first sensor is critical. If you are too close the shot blast will mess up the reading. Too far away and the shot group breaks up and some chronos can't catch it or you shoot the chrono. I have tried it with 28-34 inch barrels with full choke and found very little difference as long as barrel front is in same location. A cylinder choke gives a slightly larger target. I use an oehler 35p (wish they would upgrade the interface for pc/phone). It has 3 sensors to allow you to verify the chrono. 1st to third sensor should be slightly slower ( typically around 5fps on mine) and consistent.

    Sunlight issue present more of a variance unless you are doing it in a light box