I use Strelok Pro along with my chrono on tablet, its a cracking app once you've got it all set up right, barrel length twist rate velocity etc etc. He's bang on with help to, replies to emails within 24 hours, good ole Boris.
I use a bendy straw on a bamboo kebab stick as a wind vane and an anenometer too, but even with all the setup it helps, but nothing beats good old practice for long range, just wish I had some chance to get out, winters coming yippee ?