I think Snowwolfe hit the nail on the head. I just don't think the thieves spending the kind of time it would take to gather supplies needed to preserve the weapons properly and do a good job of burying them. They most likely wrapped them in tarps and buried them that way. I don't think they would have more than one night to do all of this as daylight would bring curiosity seekers around to see what is going on.
Battis, I have 6 or 7 metal detectors so if you are really serious about this, I will send you one if you pay shipping.
Ole Jack