I've had one of the big blue enamel percolators for decades. I don't use it much, and when I do I mainly use it for boiling water, rarely for making coffee since I'm rarely in a large group.
Most of the time, I use one like this:
(You don't have to make espresso with it, you can use less grounds and make a more "normal strength" coffee. They make larger ones as well, but when they say "6 cups" they mean "6 2-ounce cups of espresso", i.e., 12 ounces.)
http://www.google.com/search?hl=en&...fVnsnzBQ&ved=0CKwBENsLKAAwCg&biw=1366&bih=622
The first problem with a regular percolator is that it will keep on percolating. As long as there is enough heat to boil, it will continue to recycle the coffee up through the grounds until you've got a nice pot of mud. The second problem, using it on an open fire - is that you can burn the coffee very easily. You really gotta keep your eye on that thing if you want a decent pot of coffee. Takes a little practice to get it right, and even so it's not absolutely consistent from pot to pot. Every morning is a new adventure in "hoping to get it right this time".
With the Italian style percolator, the water starts in the bottom compartment, and ends up in the top compartment as coffee. Once through the grounds and that's it, doesn't recycle the coffee back through again. Also, you won't burn the coffee since it doesn't sit on top of the fire - once it percs, it's up on top.
In any case, I don't make coffee on a "camp fire". I either pull aside a bed of coals to set the pot on, or make a small cooking fire. Big fires are great for wieners and marshmallows and keeping the snarks away, not great for cooking.