The figures on each end are from the Caesar US Army set. The ones in the middle are from the recent Italeri US Army set. Bigger, but not horribly larger.
Caesar Miniatures officer figure. Map case and pointing, he could be a good man with the heavy .30 caliber tripod mounted machine gun, or as an artillery forward observer.
The .30 caliber HMG is one piece and the firer is another. Gun and tripod as one part. Very nice. The gun can be fired this way, the sights are rather tall. They can also use tracer. Prone was also very common. The tripod was adjustable.