You need to check the PRIMER. The nail test normally consists of just popping the primer in an uncharged empty case at the nail.
And now you are down to 30!
Anyhow, given the vintage of the ammunition and the fact that B West found it necessary to pay a flunky to go through what was probably a few thousand cases of this stuff to strike out the 'non' on EVERY 16 round box in EVERY case they had before they sold it, my money is going to be heavily on the fact that it is going to be corrosive.
I have mostly only plinked with that stuff, so I can't tell you for sire how it groups. The half case or so I have shot so far has been sure-fire, and I was usually able to hit what I was aiming at (or came darn close) when I was plinking with it.
I do also recall that 'skybusting' at a random target (usually a highly visible rock or a clay pigeon that was 'pissing me off') on a backstop about 70 yards away from my position usually resulted in a strike within a foot or less of what I was aiming at. Not really scientific, but it is what it is.