I don't believe there is quite that much precision in the knowledge of the battlefield and units.

1. Unfired Cosmopolitan rounds were found in small numbers in a cluster on the far east end of the field with a few fired rounds to the south, and another wider group of roughly equal numbers southwest of the Gallagher groupings. This could mean they were employed by different companies/regiments, or that the scatter in the southwest group was the result of a unit pursuing post charge. This is consistent with the 4th Iowa as I understand it. (I drew this conclusion on my own from the data/figures in the Lees report, and then found that he had a similar suggested interpretation.)

2. It isn't clear where the single confirmed fired Henry case would be in these groups. It was found in a prior survey if I'm reading it right. Since it is the only intact fired Henry/Ballard case recovered, I would caution against applying it too broadly. This is especially true since Lees describes the recovered rounds as resembling Ballard pattern instead of Henry. Now this could simply be the result of the interchangeable ammo combined with the existing logistical connection of Ballard ammo to the KY regiments next door to Missouri. Roughly twice as many Ballards were produced as Henry's during the war. Bruce Nichols has related the contemporary documentation of captures of Ballards from a related MSM regiment.

3. An area that I wonder about is relative land/groove pattern of the Ballard vs. Henry. Were they identical? The recovered rounds were all five 0.10 inch lands with five 0.175 inch grooves. I've not yet found ACW specs for these .44 caliber barrels (way too much noise in Google searches) although I did find a modern examination of a period Ballard in .46 caliber with five lands and grooves, plus an image of another that seems to show the same.

4. I don't know if we can tell if the 1st MSM had a mix of Burnsides or if this was mixing with a regiment from the adjacent/overlapping brigade. Lees notes that the 3rd Iowa is known to have had this arm (although a later typo incorrectly places this grouping as from the 4th Iowa.) However, on the face of it the pattern matches the expected 1st MSM position and Henry/Ballard pattern well.