If you are zeroed at 100, and it takes 2moa to get to 200, can one accurately determine drop at 300?
Rifle Scopes can drop data be extrapolated accurately?
- Thread starter hydro556
- Start date
Re: can drop data be extrapolated accurately?
It depends. If I assume that you are shooting a .308 with a 175 Sierra Matchking at a muzzle velocity of around 2600 fps, I can be pretty sure that you will need about 4.5-5.0 MOA at 300 yards on a standard day.
However, that's based upon experience, not upon extrapolation.
Two hundred yards is way too short a distance to base conclusions about performance much farther.
It depends. If I assume that you are shooting a .308 with a 175 Sierra Matchking at a muzzle velocity of around 2600 fps, I can be pretty sure that you will need about 4.5-5.0 MOA at 300 yards on a standard day.
However, that's based upon experience, not upon extrapolation.
Two hundred yards is way too short a distance to base conclusions about performance much farther.
Re: can drop data be extrapolated accurately?
While I prefer to shoot for dope, sometimes that isn't possible prior to a session.
Do you know of any online calculator or excel spreadsheet that will extrapolate long range trajectory from actual close range dope or from a couple long range points?
For instance my long range shooting spot has several areas from 600-850 that I can set targets. Other areas are not acceptable due to ground cover or defilade. Currently I have just been checking my actual dope against the calculated dope from my ballistic computer and tweaking the inputs to match.
While I prefer to shoot for dope, sometimes that isn't possible prior to a session.
Do you know of any online calculator or excel spreadsheet that will extrapolate long range trajectory from actual close range dope or from a couple long range points?
For instance my long range shooting spot has several areas from 600-850 that I can set targets. Other areas are not acceptable due to ground cover or defilade. Currently I have just been checking my actual dope against the calculated dope from my ballistic computer and tweaking the inputs to match.
Re: can drop data be extrapolated accurately?
Thanks lindy, I agree. I have data from other rifles shooting 175s but this with 168s. And only 20" of barrel. I only managed to get dope to 200 due to time constraints. Right now, I am about 20 miles south of the ia boder in northern mo oveerlooking 600 yards of bean field wishing I had more data, lol
Thanks lindy, I agree. I have data from other rifles shooting 175s but this with 168s. And only 20" of barrel. I only managed to get dope to 200 due to time constraints. Right now, I am about 20 miles south of the ia boder in northern mo oveerlooking 600 yards of bean field wishing I had more data, lol
Re: can drop data be extrapolated accurately?
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Do you know of any online calculator or excel spreadsheet that will extrapolate long range trajectory from actual close range dope...</div></div>
No.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">... or from a couple long range points?</div></div>
Oh, sure. JBM will work, and so does Field Firing Solutions.
I don't bother with chronographs any more, if I can get long-range dope. Chronographs are not very accurate, anyway.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Currently I have just been checking my actual dope against the calculated dope from my ballistic computer and tweaking the inputs to match.</div></div>
Me, too. If you have good BC data for the bullet, like the G7 BCs in JBM, and can shoot a target at 800 yards or more, just get the longest dope you can, and adjust the muzzle velocity in JBM until it matches the longest dope you got.
Do that, and you'll have pretty good predictions until the bullet gets into the transonic range.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Do you know of any online calculator or excel spreadsheet that will extrapolate long range trajectory from actual close range dope...</div></div>
No.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">... or from a couple long range points?</div></div>
Oh, sure. JBM will work, and so does Field Firing Solutions.
I don't bother with chronographs any more, if I can get long-range dope. Chronographs are not very accurate, anyway.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Currently I have just been checking my actual dope against the calculated dope from my ballistic computer and tweaking the inputs to match.</div></div>
Me, too. If you have good BC data for the bullet, like the G7 BCs in JBM, and can shoot a target at 800 yards or more, just get the longest dope you can, and adjust the muzzle velocity in JBM until it matches the longest dope you got.
Do that, and you'll have pretty good predictions until the bullet gets into the transonic range.
Re: can drop data be extrapolated accurately?
Patagonia will do the 2 different range dope but you technically would need your zero so it is 3. As you get to real long distances your BC can change based on velocity so the longer the "check" ranges the more accuracy it will produce.
Patagonia will do the 2 different range dope but you technically would need your zero so it is 3. As you get to real long distances your BC can change based on velocity so the longer the "check" ranges the more accuracy it will produce.
Re: can drop data be extrapolated accurately?
Changing the BC with velocity is only necessary if you're using a type of ballistic coefficient which doesn't fit the kind of bullets you're shooting. That's why Sierra supplied sets of G1 BCs in velocity ranges for their Matchkings - the G1 BC doesn't fit well relatively long boattail bullets.
A G7 BC fits those bullets much better.
Changing the BC with velocity is only necessary if you're using a type of ballistic coefficient which doesn't fit the kind of bullets you're shooting. That's why Sierra supplied sets of G1 BCs in velocity ranges for their Matchkings - the G1 BC doesn't fit well relatively long boattail bullets.
A G7 BC fits those bullets much better.
