Impact Data Book Question

[JYBuilders]

I just purchased an Impact Data Book and was flipping through the pages when I noticed something I could not figure out. First let me say that I am new to the Mil-Dot system, and all that comes with it, so this may just be ignorance on my part.

On the premade ballistic charts, the very bottom shows the environmental conditions where the data was gathered, and that they used a 100 yard zero. My question is this: If they used a 100 yard zero, would there be any recorded bullet drop at 100 yards? The chart shows no adjustment is needed, but that there is drop(i do not have the book in front of me, so i can not give exact numbers). Is the "100 yard zero" a typo and the actual results are the product of a shot with the bore aligned with the target? For the life of me I cannot figure out why the Mil adjustments do not equal the bullet drop at the given distances provided.

What is more likely, is that I do not know what I am doing. So if you have a correction for my problem, please let me know.

Thanks

 

[NOMAD]

Re: Impact Data Book Question

Thank you for your interest in our products. I am glad you like your book and I know that you will benefit from the information found inside as well as the data you collect in it.

To answer your question:

When the bullet leaves the barrel it crosses the line of site twice. When you zero your rifle, the barrel of the rifle is angled in order to compensate for the bullet drop of the intended point of Impact. The amount of angle is determined by numerous factors the most important ones being sight height, muzzle velocity, bullet weight, and BC.

The mils/moa adjustments in the charts take into account the arc of the bullet after you have zeroed at a prescribed distance. In this case 100 yards.

In the case of flat bore axis:
If you had no scope on the rifle and a laser pointed at the target thru the barrel the bullet would drop the prescribed drop below the laser line of your intended point of impact. So if the 100 yard drop was 1.8 inches at 100 yards, that bullet would drop 1.8 inches below the laser line.

The drop numbers you see in our charts are more or less feel good info that allows us to see roughly how many inches your bullet is truly dropping at a given distance. We included them for the fact that people always wonder or talk about how much a bullet is dropping at a prescribed distance. So that’s why they are there!

The drop in inches is more relevant to a ballistic program which mathematically calculates your actual come ups in MILS, MOA, ect.

The drop numbers in the charts should not be used by you the shooter in order to try and calculate you actual come up at various ranges. If you do, your math will not work out and you will MISS your intended target.

I hope this answers your questions. If you need any further help or have any questions please drop us a line.

Tony