Ok, Lets give it a go.
This picture shows the backs of three bladed Buck stockman as produced by the Camillus and 1985 to 1988 method. Brass liners, two springs. One for clip blade and one for spey and sheepsfoot blade. Brass liner in the middle to help keep things aligned. Sometimes there were two liners inside the scale on one side to give extra room in the blade well for the spey and sheepsfoot blades to be able to fold down beside each other. Look at model on left and you can even see where a thinner spring was used along with a thinner blade. This was not random but a was a overall design change. Now that my memory is kicking in, I believe this thin one is a 1985 to 89 425m era Buck made knife.
Buck decided they wanted to improve the situation on their slipjoints and BEGINNING in 1989 they started making SOME of their slipjoints using all stainless steels, liners and springs. They also decided that their blades were going to have a spring a piece and stay unbent or un-crinked as the term is described. So they started putting in a spring for each blade.
Here is a photo of a crinked blade setup
At this time of transition, changes occurred at slightly different times for the different models. Now remember we are only talking about the 301, 303 309 and 305. When the stainless liners, one spring per blade era got going Buck also started making the black sawcut slipjoint models listed above with a shield that was actually a pillar of metal attached to the liner. The scale was pressed over what we like to call the Knife, Bolt and Hammer shield.
Another reason to change was to have liners that could 'grab' the scales via melted rivet like spots that went thru holes in liners. Not possible for brass.
These changes all occurred during the early 1990s. Also changed was the blade metal from 425M to 420HC. Maybe someday I will organize all this to the finest detail and make a chart that will be the final word......Always remember what someone told me long ago.....Let the knife tell you the story.....
Next question........300