Interesting....................
Well, How about some info., heck there may be one or two people I haven't talked to yet.......
Supra's photo is of the first model Buck folder, not marked 301 but a 301 sized knife that we all call a 301 from 1967. That knife was a contract made for Buck by Schrade knife that set the 'basic' design for the long future. The Schrade version had typical Schrade era 'S' shape. But it had what Buck considered in the end as a flaw. Hidden blade(s) pivot pins.
Cross-section of Schrade/Buck bolster. Both the pin and liner can warp under heavy use.
You had to take the knife completely apart to put in a new blade. With Bucks vaunted warranty that led to a lot of repair time..... so after about four years Buck switched contractors and went with Camillus which made a stockman with pins thru the entire bolster and made blade replacement easier. In late 1985 Buck tooled up its own factory to produce four slipjoints knives, the 301 and 303 were two of them. Beginning in 1986 the Buck 300 Series, that were made in the factory (some models still made by Cami up to 2000), carried date code symbols on the tang, following the model number. Production of that black sawcut stockman knife continues today, along with several kissing cousin versions. Older knives were always made with SS blades, early models had carbon springs before everything went stainless. Blade metal was whatever Schrade and Camillus used. (Here is ID note....if it ain't got a date code, Buck contracted it)
I always wished the Schrades were 440C, but twist my arm behind my back and I will only admit to 440a blades till Buck took over production. Buck first used 425M steel till about 1990. Paul Bos had taken up residence in the Buck factory by then and a switch to Bos heat treated 420HC was made and that metal continues to be used today.
Photo is of the Schrade versions # 2 and 3, these are really version two with two variations. Lets just call them version 2 and 3. Number two has lost the grooved bolster of the first model but has BUCK stamped on the reverse of both secondary blades. Number three variation has the reverse tang blank. They look the same from the front.
Camillus made the 301 from 1972 to 1986. Which is the most commonly seen discontinued 301 at knife shows and on auctions sites. Rub the bolsters on your jeans to heat it up then breath your moist breath on the bolster to see the pivot pins if you are not sure what your have.....
300Bucks/ch
I'm also a fan of the Buck 301 ...as well as the 
