7.62x63 (.30-06) M2 AP "Special Ballistic Test"

I just came across these images.
The markings seem interesting.
Does anybody know if these were loaded with new propellant and primers or other specs and which components were used?
Or does the “mixed lot” imply these were just repacked normal cartridges?

Image source: internet.


Is the word “Arsenal” usually abbreviated “ASL”?