A steel that has been used by Busse but not for quite a while and with an alphanumeric designation? = ATS34
Either Dan really did hurt his back or that is another hint.
Full splits= folder.
A Scrapyard folder of ATS34
I believe Dan corrected somebody else above similar to your suggestion of ATS34 by saying: "That would be letters and numbers".
The implication is that the steel is NOT letters and numbers, but it is Numbers and letters.
So, not alpha-numeric: Not ATS34, and not SR-77, SR-101, A2.... etc.
But, numeric-alpha
Possibly:
420 series
440A, 440B, 440C
154CM
12C27
50100-B
440V (aka S60V)
420V (aka S90V)
10V
3V
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Full splits= folder.
A Scrapyard folder
Interesting thought to tie "Full splits" to folder.... Maybe, but I just somehow doubt it (?????).
- could Jack imply Jack knife? - anothe "possible" hint to folder (????)
In any event, I don't think it is ATS34.
.