I believe it. Carrying around poles was probably a bigger hassle than cleaning a little mud out of a musket barrel. In the posted image, though, I thought that these guys were or had been encamped for a longer duration. One would think that it would be more logical to grab some scrap wood (seems to be some laying around in the area). I could see using the muskets as makeshift tent poles temporarily. Maybe these guys just showed up and didn't feel like taking any more time than was necessary to get something erected to keep the frost off.
I also love all the "ghosts" in the background. There is so much to see by what is not seen in these old photos. The guy lying on his side is a very cool detail - was sitting up, maybe heard a photo was being taken, and quickly got rid of the blanket and struck a pose. I love it!
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