Well; I use mine ALOT--like several times a week in shootable weather. it is an instrument that can give you data that no other chrono can that is not a radar type unit--most of the others are basically snap-shotting the velocity of the bullet between point A and point B--the labradar actually tracks the bullet and returns in-flight data. That's it's big advantage in a nutshell.
Aiming the unit--that is perhaps one of the hardest parts, the v-notch leaves a lot to be desired--I took a piece of plastic tubing and taped it into the notch--that helps a bit. Aiming is also a function of getting the bullet to intercept the active radar "beams" so that is why it's ideal to use the ignition report to trigger the unit; it then calculates the muzzle velocity. Otherwise, the bullet has to travel a ways to intercept the beams since the muzzle is to the side of the unit.
Using the muzzle blast to trigger the unit took me a while to get used to--but I almost always position the gun correctly now on first try, I sometimes will drop a few distance returns which generally need a tweak of the unit's position to track the bullet all the way to 100 yds (the usual limit of the unit I have). I generally set the muzzle distance to unit setting at 12" and just leave it there--that basically sets a default of maximum distance to bullet intercept for tracking the path. Positioning the muzzle of the gun is a function of the muzzle type--target and linear comps, as well as pistols/handguns without a muzzle device will generally need to be have their front plane close to the front plane of the radar unit. Muzzle devices likes brakes, compensators, suppressors etc that send blast to the side or behind need to be further forward of the unit to avoid damaging it; the "parabolic" side/back blast of the report will be enough to trigger the unit. Mine has plenty of carbon "patina" on it but has never failed mechanically--other than a blast once blowing the external battery pack off the unit (my fault for getting my 458 socom brake a wee bit too close to the unit). The biggest engineering flaw IMO is the use of the flimsy connector port--the same type used in cell phone cables--if the battery falls or is blown of the unit--the connector is easily deformed which can create power connection problems. I don't like the rubber port cover either which puts a downward force on the cable connector--also potentially creating a leverage point for deforming the connector. I use a long cable for connecting the external power battery to the unit and simply set it to the side on the table or better yet on the ground--it has less distance to fall if it's already on the ground.
Another "gotcha" in the learning curve is the unit's tracking of projectiles--it works very well for everything from archery arrows to higher velocity rifle projectiles--but it has a software algorithm of some sort that requires the choice of either handgun or rifle when selecting the default projectile velocity type. Problems can arise when your handgun (like my 9 x 25 Dillon) can exceed "common" handgun velocities--or your rifle projectile is a fairly slow one--as might be expected in a reduced load. That transitional borderline is around 1700 fps +/- 100 fps--it will be obvious if the unit is having trouble when it returns impossible velocity figures (or else your next shot might be your last if there's a real hyper-velocity issue!
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Another thing that I hope they improve at some point--as far as I know once you add a new group you can't go back and record extra shots to a previous group. That's a PITA to me if I need to record an extra group for the missed shot.
For all it's short-comings--it's still an instrument "par excellance" for determining what your handloads are actually doing.
