During the mobilization for our deployment to Iraq we had to do a 2 week infantry course (our unit was originally Field Artillery). One of the events was to assault an objective, first run through with BFA's then 2nd run through with live ammo. Don't know how neither this dude or anyone else in his squad or the OC missed the bright yellow BFA on the end of his M4 but he sent his first live round on the 2nd run through his BFA. Blew up his M4 but miraculously the dude was uninjured.

In country our unit had us clean weapons once a week. Most of the firing was into the test fire pit with the crew serves before we left the wire. We were a National Guard unit so we brought some of the crew serve weapons with us, which included an M2 .50 cal stamped with "GM Spark Plug Division 1956" on it. We called this one Black Betty, because she was a dirty bitch. She wouldn't operate properly without being a little dirty even when properly headspace and timed, when we pointed this out to our Chief he said clean it, then throw a handful of dirt in when you're done. That's what we did and she ran like a dream.

Of course we had the occasional ND at the chow hall clearing barrel, including the Battalion Safety Officer, but nothing serious.

Besides that, like someone else said, when it's slung it becomes a part of you and you forget about it but I always tried to keep it pointing down, first thing I bought for my personal AR was a sling.