The Australian Owen submachine gun was once of the best overall SMG designs of the Second World War, and when Australia decided to replace them in the 1960s, the new F1 design have big shoes to fill. The basic configuration of the top-mounted magazine remained, but coupled with elements of the Sterling SMG. The F1 used a simple sheet metal tube receiver with elements welded on, and a typical open bolt, blowback operating system. The unique rear system of separating the recoil spring from the main receiver body in the Owen was not included, instead using a basic open tube and large diameter mainspring. The sights are curiously still mounted to the right side of the gun, with a thing folding rear sight and a front sight affixed to the magazine well. These simplifications did have the effect of lightening the F1 compared to the Owen, which is a nice improvement. The F1 was manufactured from 1962 until 1973, with a total of about 25,000 made. It served in Vietnam and through the 1990s, when replaced by a variant of the F88 Austeyr. All reports are that it was a perfectly adequate submachine gun, but it did not earn the affection of troops like the Owen had.