3 shots = Help! Help! Help!--Well.....
A number of years ago the WI Dept of Natural Resources did a study during the gun deer season, of 3-shot firings. Wardens sought out each shooter who fired 3 shots, close but evenly spaced. (No word on whether they found all such shooters--bet they did not!)
Anyhow, the finding of the study was, that 3 shots fired during daylight (when hunting deer is legal in WI) means the hunter saw a deer and missed it at least twice. That's all.
However, at night (hunting deer illegal in WI,) 3 shots meant SOS, oftener than not. Could also mean a poacher, but that's unlikely while there are a zillion hunters in the area.
IIRC from my Boy Scout days, any series of 3 in a row, where it would be unusual, is supposed to mean SOS--3 shots, 3 whistles, 3 flags, 3 fires for a rescue aircraft to spot, etc, etc. Unusual would be the key. Shots during open hunting season would hardly qualify as unusual.
I imagine that todays' outdoorsmen would generally use a cel phone or i-pod, or radio, instead. There has been at least one rescue from Mt. McKinley, in Alaska, called in by cel phone.
BUT--IMHO, the outdoorspeople of today ought to at least be aware of the low-tech signal, as well. Otherwise, what do you do after falling in the swamp, breaking a leg, and drowning every battery you have along??