Nippon Kogaku Nikkor-H 300mm f/4.5 non-AI
Screw 1 circled in red allows front element to unscrew at red dashed line. Screw 2 in red does not seem to allow anything to come apart. Turning the focus ring causes the lens barrel to extend in direction of gray arrow. Focus ring also extends toward front of lens, in direction of gray arrow at the same time. Screws circled in blue (there are around the focus ring) may be used to remove the focus ring, not sure.