Range Report Holdover from 400 yard zero

[Tempest 455]

Question on holdover with my current zero. My rifle is zeroed at 400 yards (thats what my range is) and we are going to do some longer distance next week. I'm testing some different ammo (at my range) so I'm going to leave the scope where it's at. However at this longer range I'm planning to use holdover and KY windage.

Looking at the chart on this page, it shows a rounded off hold over of 5 mils for 600 yards when using a 100 yard zero.


http://www.millettsights.com/resources/shooting-tips/calculating-mil-dot-reticle-holdovers/

Is this a linear thing? Looking at the chart, with a 400 yard zero (to get 200 more yards) would I only need 1/2 mil to get to 600 or does the ballistics of bullet drop not take into consideration the first 400 yards of travel.

Sorry if I'm not explaining this as clearly as possible but I'm just trying to figure out how many mil dots I need to get out to 600, 700, 800 etc. with a 400 yard zero?

 

[George63]

Re: Holdover from 400 yard zero

if you cannot give the MV and BC anyone answering the question will be making a bigger guess than you

and no, bullet drop is not a linear function (straight line) for drop vs distance traveled - it is a quadratic function (curved line)

bullet drop is closer to linear for time vs drop

 

[redbullitt]

Re: Holdover from 400 yard zero

That drop is going to get steeper and steeper and steeper with distance.

Definitely need some info on your projectile and rifle etc. Do you have access to a decent ballistics program?

 

[Tempest 455]

Re: Holdover from 400 yard zero

Thanks. That's what I figured.

I use JBM for a program and it's got me close when I adjust for MOA on the scope. As posted, I'm just trying to find out if I can mil dot this time out.

I'm shoooting .308 Black Hills 175g, BC approx .460, 2650 fps. out of a Savage 10BA. Scope is zeroed at 400.

 

[Trigger Monkey]

Re: Holdover from 400 yard zero

Well checking out my handy dandy FDAC with a 175 going 2650fps this should get you close.

400 - Zero
500 - 1.0 mil of holdover
600 - 2.2 mil of holdover
700 - 3.5 mil of holdover
800 - 5.0 mil of holdover (Top of thick post)

If you haven't checked one out already I highly recommend the FDAC (Field Density Altitude Compensator). I've been using one for a while now and trust it to get me on target in just about any weather condition, any where. Several sponsors here on the Hide sell them like Triad Tactical and Impact Data Books so they're easy to come by. Good luck and hope this helps.

 

[Tempest 455]

Re: Holdover from 400 yard zero

Thanks!