Fujimo,
Here's my home-made list of 315s, seven versions. From oldest to newest. If anyone can improve on this I would appreciate hearing. There is at least one rare special version I won't list to avoid confusion. I have looked hard and have not 'collected' a couple...Ages 1972 to 98.....Metal bolsters oldest.......300$s
1. Metal bolsters, Tang marked BUCK Made In USA, 315 on opposite side, solid spring
2. Metal bolsters, tang marked BUCK 315 USA, solid back spring
3. Metal bolsters, tang BUCK 315 USA, partial serrated blade
4. Metal bolsters, tang BUCK 315 USA, SPLIT back spring
5. NO metal bolsters, BUCK 315 USA, no scale rivets, BUCK hot pressed into one scale
6. No metal bolsters, BUCK 315 USA, no scale rivets, nothing marked on scale, Solid spring
7. No metal bolsters, BUCK 315 USA, two scale rivets on scale, Split spring