Ballistic calculations

Briguy34

Private
Minuteman
Oct 4, 2020
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Currently I use privy partisan 145gr 308. most ballistic calculators do not have bullet data for this ammunition. I tried to research and figure out how to input bullet data into the calculators and match up the drop charts i produced to real world data. nothing seemed to work and now im left with more questions than i started out with. luckily i found an app that has bullet data for my ammunition but i still want to know how to properly input data in the future when i start making custom loads

can anyone here post "custom" bullet data for :
PPU M80 7.62×51/308 Win Ammunition 145gr FMJ BT
so that I can spot where i was going wrong?

can anyone explain the different ballistic models? for example G1 or G7? the only real info i can find on the models is what kind of bullets the models are for. when pressed for explanation all i hear is each model is a bunch of mathematical voodoo. id would like more in depth analysis

can anyone link me a good ballistic coefficient calculator? i think i understand how it works but the calculators i have found are obviously crap. for example: http://gundata.org/ballistic-coefficient-calculator/ this one wont let you input the diameter correctly

also if you can tell me what kind of setups and gear you have that would be great. I am running an RPR in 308 with an atlas bipod and vortex razor gen 2 and a bubble level, there is a killflash coming in the mail. i have a bushnell conx rangefinder and a mildot master for ranging. what else should i get?

thanks for your help guys
 

Skookum

Jack Booted Thug...Crushing the American Dream
PX Member
Minuteman
  • May 6, 2017
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    With that ammo you don't need a ballistic app. You need barn doors to shoot at.

    But Since you asked, BC is going to be around . 400 G1.

    Without going into it, G7 is roughly half of G1. Different bullets are used as reference models.
     

    Skookum

    Jack Booted Thug...Crushing the American Dream
    PX Member
    Minuteman
  • May 6, 2017
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    Try zero at 100, 0.5 mil 200, 1.2 mil 300, 2.2 mil 400, 3.3 mil 500.

    You will be close enough to make corrections.
     

    Briguy34

    Private
    Minuteman
    Oct 4, 2020
    6
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    Try zero at 100, 0.5 mil 200, 1.2 mil 300, 2.2 mil 400, 3.3 mil 500.

    You will be close enough to make corrections.
    I already have a good bdc chart. what im trying to figure out is what I did wrong when i entered data into the custom bdc calculator
     

    Briguy34

    Private
    Minuteman
    Oct 4, 2020
    6
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    With that ammo you don't need a ballistic app. You need barn doors to shoot at.

    But Since you asked, BC is going to be around . 400 G1.

    Without going into it, G7 is roughly half of G1. Different bullets are used as reference models.
    i thought G7 was for bthp, ppu is bthp. why should it be set to G1?
     

    Skookum

    Jack Booted Thug...Crushing the American Dream
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    Minuteman
  • May 6, 2017
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    i thought G7 was for bthp, ppu is bthp. why should it be set to G1?
    Until you hit transonic they track together. Either one will get you a good solution. The ammo you are shooting isn't accurate enough for any of this to matter. But even if it was, it still wouldn't matter until you were down to about 1,400 fps velocity, at whatever distance that happens with that load.
     

    Briguy34

    Private
    Minuteman
    Oct 4, 2020
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    Until you hit transonic they track together. Either one will get you a good solution. The ammo you are shooting isn't accurate enough for any of this to matter. But even if it was, it still wouldn't matter until you were down to about 1,400 fps velocity, at whatever distance that happens with that load.
    thank you, im learning. so it may be that this app i used just defaults everything to g1 because most people dont shoot far enough for it to matter
     

    Skookum

    Jack Booted Thug...Crushing the American Dream
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  • May 6, 2017
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    thank you, im learning. so it may be that this app i used just defaults everything to g1 because most people dont shoot far enough for it to matter
    G1 was the standard for a very long time (since about 1881 I believe?) . G7 came into common use within the last 15 years or so.
     
    Last edited:

    Briguy34

    Private
    Minuteman
    Oct 4, 2020
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    yes this is one of the many websites and apps that i tried. if you dont mind, can you fill out this form to fit the following BDC chart? i want to find out what i was doing wrong
    i will post my current chart in a minute
     

    Skookum

    Jack Booted Thug...Crushing the American Dream
    PX Member
    Minuteman
  • May 6, 2017
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    Were you trying to use the bc calculator or the trajectory calculator?