it was probably done on good presentation grade rifle that were built back then, given the quality of finishes found on fine furniture of the period, but for the common man's shootin' iron, it probably was considered a waste of time and labor and of course there was no time for it during the times of the revolution.
personal, I feel that we are not making guns to be used in that time, so whether it is HC or not, producing as finely finished a stock as we cam do is much more Period Correct for our current recreational use.
if I came across a gun that was currently built and it lacked a good finish on the wood, I would consider it to be of poor quality simply because all long guns built today, a presentations of what was built back then and I consider that being a "presentation grade" rifle. also, if I was building a rifle for myself or someone else, I would not feel right not putting as good a finish on the stock as I was capable of doing.