Using the correct terminology for historic gear is only of interest to re-enactors, and among that group only those who are fairly serious about it.
If a man's only interest is in shooting the guns in one way or another, competition, hunting, casual plinking, then it seems less important, to me. It always puzzles me why those people are even such conversations. All they usually have to offer is rampant speculation, personal experience and armchair imagineering.
Reading through all 4 pages of this thread I find only one post with anything which qualifies as 'evidence' in the form of original quotations, and that was examples of what the bag was actually called in the day, possible bag not one of them.
There are original quotations available which can shed light on the question. It seems "possibles" bag is a legitimate historic term which may have originated in early 19th century, maybe as early as 1830, but not in 18th century. I think "mountain man jargon" is probably a good way to think of it. The problem we have today is not that people are using a term which never existed, which originated with the Buckskinners of the 1970s, or that was invented by some movie scriptwriter. It's that they are applying the legitimate term to the wrong thing.
Rich had it right, I think, it was used for the mountain man's luggage, his suitcase, if you will. Here are some original quotations which seem to bear out what I just described.
_Life in the Far West_, by George Frederick Augustus Ruxton: 1846-47
“For many years after he had deserted his home, La Bonté had cherished the idea of again returning to his country. During this period he had never forgotten his old flame, and many a choice fur he had carefully laid by, intended as a present for Mary Brand; and many a gâge d’ amour of cunning shape and device, worked in stained quills, of porcupine and bright-colored beads---the handiwork of nimble fingered squaws---he had packed in his possible sack for the same destination, hoping a time would come when he might lay them at her feet.”
William Drummond Stewart's fictional book _Edward Warren_, published in 1854 but based on his several years of Rocky mountain experiences during the 1830's, "...my gaudy cottons having confronted the glorious sun until sunk from the contest, were ready to be re-consigned to the possible sack."
And the really important one, with the term used six times and defined by the author in a footnote, page 111.
_Wah-to-yah, and the Taos Trail: Or, Prairie Travel and Scalp dances, with a look at Los Rancheros from muleback and the Rocky mountain camp-fire_, (1846-47), by Lewis Hector Garrard
pg. 111 "On the 8th, we packed our robes, and “possibles” **, and, by eleven o’clock, the wagon, with its two yoke of half-famished oxen attached, ready for a start, was on the top of the hill."
**Personal property
pg. 48 "Without saying a word, or going in the lodge first, we unsaddled in front of it, putting our “possibles” in the back part, the most honored and pleasant place, for there is no passing by, or other annoyance."
pg. 81 "The foibles and virtues of mutual acquaintances in St. Louis, were freely descanted upon, during the discussion of some cigars, found, unexpectedly, among my “possibles” at the Fort, as we crossed our legs on the ground that night before the cottonwood logs."
pg. 144 "Considering his neighbor's possibles “on the prairie” with him--- his own at their entire disposal; and. though coffee. sugar. tobacco, and other luxuries are high-priced, and often purchased with a whole season's trapping, the “black water” is offered with genuine free-heartedness. and the last plug of tobacco subjected to the rapacious knife of the guest, as though it were plenty as the rocks around."
pg. 288 "Putting my possibles in a wagon, I received my amount of coffee, sugar, etc., from the affable Doctor Hampstead."
pg. 306 "Smith, who had been showing, in private conversation with me, a fear of losing his hair, gave notice of leaving with this train, which stopped while he collected his possibles."
So, in the fur trade era the term “possibles” was used for one’s personal property, and the term “possibles sack” or “possibles bag” was then appropriate, but it was never used for the shot pouch. And it shouldn’t be, today if you are really interested in recreating the experience of the old boys in their time. If you aren't, then let it all hang out, who cares. I certainly don't.
Now, if your shoulder bag is where you carry your sun-bleached clothes, cigars, coffee, sugar, tobacco and gâge d’ amours, then maybe Possibles Bag is appropriate.
Spence