470,
On the copy of the Jeffery records I have seen at Champlin Firearms, almost all of the barreled actions were acquired from Leonard. Page after page listed Leonard.

I know Jeffery made very few if any.
As I understand from you that the actions were finished by this other maker for jeffery?

The best way to denote a leonard action is by the 4 digit number on the under rib near the barrel loop. There may also be a very small initial on the under rib at the barrel flats.