#9 Ballistic Solvers: How to Use Prediction Machines

hereinaz

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As long range hunters, if we want to hit a target far away, we need the ability to predict where the bullet will be in time and space and aim the rifle so that the bullet falls and drifts into that specific spot. Inside 300 yards, with a maximum point blank zero, many hunting cartridges are good enough to "hold hair" and press the trigger. Beyond that, the time of flight of a bullet allows environmental factors to act on the bullet so that we need to adjust the direction of fire so that it will impact with our point of aim.

For instance, take gravity. Gravity is a constant force that can easily be accounted for any object. For a bullet fired straight out at no angle, you just need to know how long it is falling, and we know how much it will drop as it travels. If you fire two bullets, that have the same BC at the same velocity, then the drop for those bullets will be identical. However, wind will cause the lighter bullet to drift further.

There are many details that go into making a ballistic calculator work and understanding how it works. I won't go into that. You don't need to have a degree or need to read a complex manual. You literally just plug in numbers and hit go. Like many things, you will figure it out as you go.

What I am going to do is encourage you to go to a simple ballistic calculator online or on your phone and just start playing with a ballistic solver. Check out all the inputs. Learn what they mean. Then, start playing with your favorite bullet and velocities. Play with wind. You can begin to see trends. I think a couple hours playing with a ballistic calculator comparing a typical 308 and a 300wm can teach you a whole bunch. Then compare them to a .243.

Online, a great resource is https://www.jbmballistics.com/ballistics/calculators/calculators.shtml. I print out drop charts and compare variable, but especially the bullet, the velocity, the wind, elevation, and temperature. Those are the variables we will encounter.

For your phone, there are many, including Applied Ballistics (which I use because of the solver and the custom drag models), Strelok, Shooter, and Hornady 4DOF. On my phone, I like to screenshot different drop charts and flip through them.

Whenever someone wants to know whether X cartridge is better than Y cartridge, I regularly go to Hornady's website and pick a typical factory offering. I load the bullet and velocity into my app, and then compare them. For all the worry and handwringing, the truth is there is very little difference in most common centerfire cartridges inside typical hunting ranges of 500 yards. Beyond that, the differences grow.

I will post up a few comparisons over the next couple of days and put them in the comments.

Once you start to figure out how they work, then you can easily take it to the range as a valuable tool. I mean, you wouldn't go to a range and that be the first time you run the bolt or drop the mag, would you?

How do you use ballistic solvers besides final firing solutions?
 
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hereinaz

hereinaz

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Here is comparison between my 7mm Sherman Short mag shooting a 180 vld at 3000 fps and a 300 PRC shooting a 212 ELDx at factory velocity of 2860. I punched in typical environmental conditions for a hunting location I frequent.

By comparing the data, you can see that the velocity of the 7mm 180 vld actually provides about the same energy on target and they both reach out to 700 yards at the minimal velocity for expanding for the bullet. There is no practical difference between the two for energy and velocity. For me, that means that the recoil penalty of the heavier bullet and additional powder provides "no benefit". I put that in quotes because cost/benefits are personal.

7mm 180 vld 3000.JPG300 prc 212 eldx 2860.JPG
 
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hereinaz

hereinaz

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Here is the data for a 6.5 Creedmoor vs. 308 win comparison. I used Hornady factory ELDx load velocity for them. In all the arguments of which is better, it certainly is valid to know that at 1000 yards, the 308 has 98 inches of more drop than the 6.5 Creedmoor. That doesn't make it "better", it is just facts.

6.5 creedmoor 143 eldx.JPG308 at 2600.JPG
 
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