+1
Alcan powder was dead & gone long before the .40 S&W was invented.
AL-5 was primarily a shotgun powder.
Burning rate falls between Universal Clays and AA #5, so it would probably work in .40 S&W if you could find any pressure tested .40 load data. But you can't.
The old Speer #6 manual listed it in a lot of calibers, but it was published way before the .40 S&W was invented.
They do show .38 Super & .44 Mag loads that are very close to the Unique loads.
However, AL #5 is slightly faster burning then Unique so DO NOT use Unique .40 S&W Max loads with AL #5.
And you do so AT YOUR OWN RISK!!
If you blow up, don't blame me!
PS: I should have mentioned to check for deterioration in powder that old.
Smell it, and if it smells like acid, and not like solvent?
Dump it on the lawn. It is nitrogen fertilizer now.
rc