Pachmayr made a mount called the Lo-Swing which mounted on the top of the receiver. This was a pivot mount, and a good one. Leupold produced the Detacho-Mount, which was one of the few simple ones. It was a top-mount mechanism, and very much resembled the mounts that are now used with Picatinny rails. In the 1930s, Weaver made a thing that everyone called “The Grasshopper,” because it employed several large, fragile springs that gave it the look of the garden-chomping insect. Later, the company came to its senses and offered a series of very simple, hugely popular QD mounts, including their own pivot mount.