The following lines were added (+) and removed (-):
580 Ranch Rifle (early version): Thin barrel, ejector in the bolt stop assembly, scope ring scallops cast into the receiver, buffer system using the recoil spring assembly, new tooling resulting in a slightly different look to the receiver (more rounded edges, etc.) 580 Ranch Rifle (early version): Thin barrel, ejector in the bolt stop assembly, scope ring scallops cast into the receiver, buffer system using the recoil 580 Ranch Rifle (later version)-581: Thicker flanged barrel, ejector in the bolt stop assembly, scope ring scallops cast into the receiver, buffer system using the recoil spring assembly, new tooling resulting in a slightly different look to the receiver (more rounded edges, etc.)Beginning spring assembly, new tooling resulting in a slightly different look to the receiver (more rounded edges, etc.) 580 Ranch Rifle (later version)-581: Thicker flanged barrel, ejector in the bolt stop assembly, scope ring scallops cast into the receiver, buffer system using the recoil spring assembly, new tooling resulting in a slightly different look to the receiver (more rounded edges, etc.)Beginning