Here are the heavy weapons from the Revell US Infantry set. Most Revell sets seem to include some form of multiple base with a heavy weapon and crew on it, and in this set there are two, a .50cal and Mortar (and two of each to boot!).
Apart from both being woefully under-manned (one man to run a mortar, really?), which is pretty normal for most sets of model soldier, these two are really rather good. The weapons are nicely detailed (the mortar bomb actually looks like one, which is rare). the .50cal in particular is outstanding, the ammo belt the loader is feeding twists in a nicely realistic way, and his Garand and water bottle are on the ground in front of him. There are even spent shell cases moulded onto the base to the right of the gun itself (although you can't really see them in the photos).
The only downside is that, being made from the usual Revell Soft plastic, assembly was a bit of a pain, even superglue doesn't like sticking these together and the mortar stand particularly had a tendency to try and bend away from wherever I was trying to put it!