Here's a chart which shows all of the decorations, medals, badges, tabs, and such awarded by the US Army. Marksmanship badges are included; the type weapon (rifle, pistol, etc.) for which the badge was awarded is hung on a bar below the badge and you can have several weapons hung on one badge. The Marines and Navy also give awards for marksmanship.

Note that the medals (i.e., decorations) themselves are not shown; the ribbons which are usually worn in place of the medals themselves are. Usually, ribbons are worn above the left breast pocket of the Class A uniform, but there are certain other awards which are worn on the right pocket (e.g., the Meritorious Unit Citation).

Minature medals -- smaller versions of the actual medal -- are worn on formal uniforms, such as the dress blues or white mess uniforms. These can also be augments by fourgerres, macrame-like things awarded in certain other circumstances (such as being an aide-de-camp to the Joint Chiefs of Staff).

By the way, the various branches of the Army have their significant colors, too: blue for the Infantry, Red for artillery, etc.

Military heraldry is a lot more complicated than most folks realize. Just think! The above discussion doesn't include unit patches and where and when to wear them!!