I'm new to the "radar"-chrono world, being a recent owner of a Garmin Xero chrono. While entering load info into the JBM Calculations page, I noticed the question: "Distance to Chronograph?" This question was likely formulated back in the days before LabRadar and the like, referring to the chronos whose sensors were located in front of the muzzle some distance. But the Garmin unit is positioned behind the muzzle, and I'm not quite sure where it picks up the shot. What should be entered for the "Distance to Chrono" question on ballistic calculators that ask it? Just want to make sure I'm putting in the proper info and not screwing up the calculations.