Long range shooting with ballistic calculators???

For those that use a ballistic calculator app, what do you change in the calculator to make it match "true statements" ? I got my 6.5 CM velocity this week. It was 2610 fps using hand loads with 140 grain Amax bullets. I noticed that the calculator is off by 2-3 tenths. Do y'all adjust the velocity to make the calculator match where your bullet impacts or scope heights off bore? I'm using the ISnipe app.

I use Applied Ballistics. I try adjustments in velocity or go back and change the bc some. Who's bc numbers are you using.

I just started using the ISnipe app. I'm using the Litz G7. Don't know if this is right or not

That's one of the most accurate one's to use. Also might punch in your info into the berger twist calculator to make sure you are using your full bc.

Adjusting velocity usually gives the best results. That is, provided you have a true BC, as opposed to Noslers inflated BCs, for instance. That is called "truing your DOPE".

I use "Shooter" $9.95 one time payment and well worth it. Though, no app is as good as a Kestrel weather meter with Horus Ballistics or Applied ballistics.

Also use jbmballistics.com. Free and easy on a PC. Very accurate calculator. You can also copy the data, then past to an Excel file and print out a neat clean chart. I keep these for all rifles in the stock pack as a backup when batteries die or any other electronic failure. You can adjust barometric pressure on jbm to have various charts for given conditions. This usually isnt very needed uless you're shooting outside 500 with a .308 Win or .270, or outside 700 yards with your 6.5 Creedmoor. They tend to shoot consistent to those ranges in a broad spectrum of environmental conditions.

X2 on jbmballistics.com Thats a great tool for the basic numbers

I use Shooter on my Iphone and Ipad. Limited experience but I have made hits at 850 with 308, 223, etc quickly using dials from Shooter.

Sterlok Pro is also a good app. Is your app capable to do a trajectory verification?

At longer ranges, correction for barometric pressure or density altitude is important.

There are some things that are easy to measure or get like scope height, velocity, temperature, altitude, barometric pressure...

BC on the other hand is a calculated value that varies some dependent on bullet form factor, velocity, twist rate, deformation when engraved by rifling..... The Berger twist rate calculator that Dee mentioned provides some good info, found out to expect 6% degradation in BC for the 6.5-284 with one of my pet loads for it.

I like to set as much of the measurable as I can then adjust the BC to match field data at 2 or more distances, the rest are pretty much on after that.

JBM is a good one, I have a couple others that have also worked well, one came with Quickloads and the other was a free download from Berger at one time.