The "crossed cannons" on the belt buckles are a reflection but the ones on the hats do not appear to be.

Those are Mills loop belts.  The USMC, if I'm getting the order right, had Lees at that time.  Lees have magazines and the belts are leather with pockets for clips.

Artillery with trapdoors.

The kersey is dark blue and sky blue - standard army colors.  The tunics appear to be the pre-1890 edition.