hepcat
Former PH, USN
...but on the flipside... my m4's rewind knob came loose after sitting on the floor for 9 hours during a transatlantic flight. The tech who repaired it thought the "micro" vibrations from the flight loosened the screw that holds the part together. It took seconds to tighten everything up again, and he was nice enough not to charge me for the service.
It was probably coming loose from use and time anyway...
I have to agree that it was probably coming loose anyway. I've flown a LOT of hours in military aircraft with M4s, and got thousands of miles on my motorcycle with my old M4-2 without any issues at all from the transport. My biggest concern was keeping them dry and relatively dust-protected.
I had my M4-2 out in the Anza-Borrego desert on a Honda 3 wheeler years ago. My whole kit was in an early Lowe-Pro bag. I was charging down an arroyo at about 25 mph when the bungee that held the bag on the cargo rack let go and my entire kit went charging down the arroyo through the sand and rocks at 25mph. After I noticed it had flown off, I turned around and went back expecting to find a dented and smashed M4-2, and lens glass that looked like a broken Coke bottle. Much to my surprise, all was intact without damage at all. I still have that bag.
A couple of years later, I was out shooting with the M4-2 on a tripod and the wind blew it over an embankment onto a pile of end-table sized rocks about 10' below. That time, the M4-2 didn't fare as well. The baseplate was dented, and a crescent-shaped crack half the size of a small fingernail appeared in the bottom of the body on one side. The baseplate still worked, and was light-tight though. The rangefinder was still spot-on. I used that camera for another ten years before I sold it.
As I said, they're tough. The Digi-Ms are probably even tougher in some ways because they really don't have as many moving parts.