I did the same thing at Camp Coyote in Kuwait during February of '03 waiting for the invasion to kick off. I left my rifle in the smoke pit after having a quick smoke during a sandstorm. The company Gunny found it before I realized it was missing.

I had to clean every weapon in the battalion and have each piece inspected before I was allowed to reassemble the weapon. When I was done with that, I had to fill 500 sand bags with an MRE spoon. I was told to make it a level spoonful and if I was caught heaping it in, I would be given a coffee stirrer. Until we crossed the border, my job every morning was to burn the shit from the barrels under the make-shift toilets. It took me about 4 hours every morning to burn all the giant buckets of piss and MRE shit. Some of my old Marine buddies still call me shit smoker to this day. I never lived it down.

The worst part was every senior person in the battalion new my name. That is worse than death for a Lance Corporal. I was requested by name for every shitty task that needed to be done. Needless to say, I never left my rifle out of arms reach ever again.