Ballistics Calculator and Bullet Drop

bowhunter57

bowhunter57

Well-known member
I ran a ballistics calculation on a specific bullet weight, bullet speed, ballistic coefficient at 50 yard increments out to 300 yards with a 150 yard zero.

50 @ .5"
100 @ 1.3"
150 @ 0"
200 @ -3.9"
250 @ -11.2"
300 @ -22.7"

Can this be trusted information?
By "trusted" I mean, if I sight my rifle in at their measurement of .5" @ 50 yards, will the rifle sights be on at the other yardages within their calculations?

Thank you, Bowhunter57
 
Definitely shoot it. Even if those numbers are perfect, sighting in at the closest distance will magnify any error further out.
 
You need to factor in the highth of the sight. i.e. scope hight above the bore line. A higher scope will make a big difference in the mid range trajectory. Typically the manufacturers use 1.5" above the bore line of sight but the ARs typically are 2.0-2.5" above the line of sight and the trajectory will be way different. Go to the Hornady website where you can factor in the scope hight for your trajectories.
 
And then you have to address atmospheric conditions along with the simple fact the original stated BC may be off as much as 20%. Shooting the bullet at different ranges and reverse engineering will help get a BC but ok course shooter error may skew the results.

There is no free lunch using a ballistic program. Gun powder and range time are the price of admission for down range success.

Greg
 
Using a ballistic calculator in this way is my favorite way of doing it. When I first started shooting long range I thought a chrono was mandatory, it's certainly not.

As stated above, testing and verifying those numbers is a must, and atmosphere can play a big role at longer ranges. When testing I always write down atmospheric conditions right before I head to the range and right when I get back, if you have a fancy gadget that reads wind, temperature, pressure and humidity at the range thats even better. At 300 yards it's probably not a big factor but spin drift will make a difference also.

I started using 140gr VLDs for the first time last year, I zeroed at 100 then got drops at 300, 400 and 650 yards. That got me very close at 950 and only 6-8 inches high at 1200.... to be fair to the calculations though, I may have been shooting a hair under 1200.
 
If you know the height of your scope centerline above the bore centerline I find the ballistic calculator to be very accurate. Obviously you need to shoot it to fine tune though.
 
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I have used the ballistics calculator app Strelock Pro for a number of years and have found it to be very accurate. In fact, when I had some CDS dials built by Leupold for a couple of my rifles I compared the ballistics they came up with using their software with Strelock Pro and found it to be almost the same.
I used it last night at the range and it really is a good tool.
 


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