Does the job! - MagnetoSpeed V3 Ballistic Chronograph Kit with Hard Case

I have been using this chrony for about 3 years now, and it's great. It takes a little bit of trial and error to get the right fit for each barrel, but once it's set, it's set.
+ Stores LOTS of data! :)
+ Can be fit to a variety of rifles
+ No risk of accidentally shooting it (like with the light-screen types)
My only gripes are....
- it only stores 99 shots at a time. If you're gathering long strings of data, you might need to collect multiple 99-shot data sets, and then upload them to your computer and compile the statistics yourself.
- on the fashionable AR-15's with long handguards (almost right up to the muzzle), you may have to remove the handguard to use the product. I don't mind doing this, but it might be a turnoff for some people.
- using it to gather data will naturally disrupt your barrel harmonics, which means that you can't reasonably expect to gather MV data and grouping data simultaneously. Again, I don't mind having to shoot separate strings for MV and precision, but I've heard other people cite this as the primary reason why they chose a different chrony system.