DougR, such historians of Old West cooking as Ramon F. Adams specifically mention brisket as being cooked in Dutch ovens. It might, for instance, be put out to cook overnight or put on when the cook got up (around 3 or 4 a.m. on a drive or roundup), cooked as long as possible, and the hot Dutch oven (minus the coals!) carried to the "nooning" spot or even to the evening campsite. Beans were cooked in the same way.

Check out Adams' Come an' get it: the story of the old cowboy cook or several others on old-time cowboy life. The cosi is always mentioned, and often there are also recipes.