Home Main Category General Firearms

Comparing computed data to the real thing.

2»

Replies

  • JasonMPDJasonMPD Senior Member Posts: 6,557 Senior Member
    I have been told by a couple of people who have forgotten more about external ballistics than I will ever know that you should always trust your observable data tenfold over any calculated expectation. My next step will be to verify this with more observations, so I will load up more ammo and repeat this test. I was shooting from a solid rested position, so I am very confident there was no vertical error due to my shooting position.

    And I do not think that Jeremy is lying at all. He is just passing on to me what his calculations yielded. If anything, I appreciate his data being contrary to my own because it gives me more information to compare to.
    “There are three kinds of men. The one that learns by reading. The few who learn by observation. The rest of them have to pee on the electric fence for themselves.” – Will Rogers
  • Big ChiefBig Chief Senior Member Posts: 32,995 Senior Member
    JasonMPD wrote: »
    I have been told by a couple of people who have forgotten more about external ballistics than I will ever know that you should always trust your observable data tenfold over any calculated expectation.

    Gives credence to the old saying.... Just because It Looks Good On Paper, In A Book Or The Drawing Board (or we could say the computer screen these days) Doesn't Mean It Will Be In The Real World.
    It's only true if it's on this forum where opinions are facts and facts are opinions
    Words of wisdom from Big Chief: Flush twice, it's a long way to the Mess Hall
    I'd rather have my sister work in a whorehouse than own another Taurus!
  • JasonMPDJasonMPD Senior Member Posts: 6,557 Senior Member
    Big Chief wrote: »
    Gives credence to the old saying.... Just because It Looks Good On Paper, In A Book Or The Drawing Board (or we could say the computer screen these days) Doesn't Mean It Will Be In The Real World.

    Well. I have the dumb. Glad I didn't get ass deep in this mess. Before I figured it out, too. My scope height is 2.75", not 3.625". Apparently I can't read a tape measure.

    With this new scope height, all the calculations yield an average of about 3.8" drop for 2620fps.

    Cancel the alarm, return everything to normal.

    I guess this thread wasn't a waste? It prompted me to re-verify hardware dimensions.
    “There are three kinds of men. The one that learns by reading. The few who learn by observation. The rest of them have to pee on the electric fence for themselves.” – Will Rogers
  • JermanatorJermanator Senior Member Posts: 16,128 Senior Member
    Well, you got it figured out now and that is the important thing. That, and I never realized how critical scope height is to those calculations-- I was just pulling a number from my butt and running with it in the past, but now I know better. I learned something from this thread as well.
    Reason obeys itself; and ignorance submits to whatever is dictated to it.
    -Thomas Paine
  • zorbazorba Senior Member Posts: 23,640 Senior Member
    I definitely learned something - which is why I like to hang out here and listen to the "talk".
    -Zorba, "The Veiled Male"

    "If you get it and didn't work for it, someone else worked for it and didn't get it..."
  • knitepoetknitepoet Senior Member Posts: 21,074 Senior Member
    Glad you got it figured out :up:
    Seven Habits of Highly Effective Pirates, Rule #37: There is no “overkill”. There is only “open fire” and “I need to reload”.


  • Big ChiefBig Chief Senior Member Posts: 32,995 Senior Member
    So 1.5" is the height most ballistic programs use as their default.

    Good article here. I guess for my purpose shootin @ 100 yards and less (Usually) the default is all I need if I ever use a software program and even if I just use the ballistics tables in a reloading manual.

    What really matters I guess if the bullets strike the where I aim.

    Maybe Ernie can chime in being a long distance shooter and tell us what method he uses.

    Click on link fer pics.

    http://www.accurateshooter.com/optics/determining-scope-height-above-bore/

    "Most load manuals and scope companies use 1.500” scope heights above the bore for their trajectory tables, since it is a very common measurement. Also most ballistic programs have 1.500” as the default measurement. If you are shooting longer distances such as 500 yards or further, the above formula should help you determine more accurate trajectories.

    Scope Height Calculation

    I personally try to keep the scope as close to the center of the bore as possible. Ideally, I like to have a 0.030” to 0.050” clearance between the bottom of the scope’s front bell to the barrel. I try different base and ring height combinations to achieve this clearance. For example on most of my Remington’s I use Ken Farrell bases with Leupold rings. I use their PRW rings for hunting and varmint rifles and their QRW rings for target rifles allowing me to remove my scope so I can also shoot with iron sights. If you have questions on how to determine the appropriate ring/base height, please call Sinclair International and ask one of our technicians for help"

    Ron Dague
    Sinclair International Reloading Instructor/ Tech and Sales Rep
    It's only true if it's on this forum where opinions are facts and facts are opinions
    Words of wisdom from Big Chief: Flush twice, it's a long way to the Mess Hall
    I'd rather have my sister work in a whorehouse than own another Taurus!
  • JasonMPDJasonMPD Senior Member Posts: 6,557 Senior Member
    For my bolt guns I keep the scope as close to the barrel as is comfortable with a good cheek weld. But the AR presents a challenge due to the top rail.
    “There are three kinds of men. The one that learns by reading. The few who learn by observation. The rest of them have to pee on the electric fence for themselves.” – Will Rogers
Sign In or Register to comment.
Magazine Cover

GET THE MAGAZINE Subscribe & Save

Temporary Price Reduction

SUBSCRIBE NOW

Give a Gift   |   Subscriber Services

PREVIEW THIS MONTH'S ISSUE

GET THE NEWSLETTER Join the List and Never Miss a Thing.

Get the top Guns & Ammo stories delivered right to your inbox every week.

Advertisement