I wouldn't plan on using it during a dust storm or heavy fog bank, lol. A full-metal jacketed round should reflect a decent amount of IR for the detector to catch. This is how modern bullet chronographs do it (measure the speed of a projectile by calculating the time it takes for the projectile to travel between two sets of IR emitter / Photodetectors)--so I don't see why this would not work. I do not think atmospheric dust would have any interference. I just need advice on circuit design, since I do not have the schematics for a chronograph.