Here's something you might find fun to play with if you get bored:
22RF 50yd Audio Chronograph BETA.xlsx
You'll need a 50yd range, a sound editor/analyzer with graphical readout - Audacity ( Audacity: Free Audio Editor and Recorder
) is totally free - and it helps if you have something that makes a lot of noise - like steel - at 50 yards. You need to hear the report and the impact (or, rather, the software needs to).
This particular chrono program is geared specifically to the .22lr at 50 yards. It opens with Microsoft Excel. Just plug the numbers in and you should get readings very close to those of a standard chronograph.
I've not tested it at ranges longer than 50yds, and so I just locked in 50 yards (unless you would like to manually change it).
Should work pretty well for muzzleloaders and slug guns - anything that might destroy the skyscreens of a standard chronograph - as well.
The average velocity should be about +/- 2% or so, but the MV is going to be off - and it'll be off even more so the further distance you move.
Have fun, and I hope to hear feedback, both positive and negative!