These could have been 4x5 polaroids, they had pretty good quality, as good if not better than any 35mm or medium format print.
As proof point, there was a type (50) where you could get a negative as well as a print. I don't recall being concerned about the quality of the negatives, the grain was pretty small. The only downside was the exposure to get a good negative wasn't one where you got a good print. So if it could get a good negative (2000dpi) for enlarging, it can make an awesome print (300-400dpi).
They are very well done. We used a 4x5 with a Polaroid back in a college Physics of Photography class (which was a blast). The creamy, grain-less images made going back to enlarging Tri-X even more painful.
I'm here for this. I didn't even know B&W Polaroid film existed and I guess that's part of the reason it looks so good. It's not your uncle's pictures of Vietnam from 1975 that became all washed out with time.
Very likely they used the larger than regular sized Polaroid such as that found in the 95 and 110 series cameras. Size would have been 3.25 by 4.25 inches. The b&w film would give a very finely detailed image.
