Some of the features of the different generations. I don't know the time scales:
1st Generation:
-CPM S30V steel
-Different thumbs stud than 2nd & 3rd Gens. 1st gen thumbstud doesn't taper like the other gens
-Grind: Saber/hollow with spanto tip. Ground by Rick.
-Blade has "R. Hinderer" etched on
-G-10 side of frame has partial titanium liner
-Slightly different looking back spacers than the 2nd and 3rd gens
2nd Gen:
-Duratech 20CV steel
-New tapered thumbstud
-Grind: Saber/ hollow with Spanto tip, ground by Rick
-Blade has "R. Hinderer" inscribed deeper than gen 1 on blade
-G-10 side of frame has full titanium liner
-Same backspacer as 3rd gen
3rd Gen. Same as 2nd Gen except:
-Grind: Saber/flat with Spanto tip. Grind outsourced to 3rd party. Sharpened by Rick. Rick has 3rd gens that were ground by him and they come in many different grinds (spanto, spear point, wharncliffe, more). You can tell the difference between a gen 2 and a gen 3 that have the same grind by Rick because the gen 3s have blank blades. There is no "R. Hinderer" on the blade.
-"Hinderer" stamped on the frame around the pivot on the full ti side.
2nd & 3rd gen scales with full ti liners can fit onto the 1st gen XM-18s, allowing you to convert the gen 1s to have full ti liners. The 2nd & 3rd gens with outsourced grinds cost $385 from Rick. The 3rd gens ground by Rick cost more from his factory than the outsourced grinded blades. XM-18s are in high demand and will generally go for higher amounts than straight-from-the-factory cost.
The 1st and 2nd gens come in the following variations:
3" or 3.5" blades
Flipper or non-flipper
The 3rd gens currently only have:
3.5" blades
Flipper or non-flipper
My understanding is that Rick is planning on having 3rd gens with 3" blades made.