Ballistic calculations

[Briguy34]

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

 

[Deleted member 113831]

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.

 

[Deleted member 113831]

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]

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]

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?

 

[Deleted member 113831]

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

That one is crap. Here is the one we all use.

JBM - Calculations

jbmballistics.com

 

[Deleted member 113831]

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]

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

 

[Deleted member 113831]

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.

 

[Briguy34]

That one is crap. Here is the one we all use.

JBM - Calculations

jbmballistics.com

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

 

[Briguy34]

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

 

[Deleted member 113831]

Were you trying to use the bc calculator or the trajectory calculator?