I would second pulling it apart and weighing the powder charge and bullet. Figuring out what bullet he was using should be possible.
But if nothing else you will be able to tell if he was using a ball or extruded powder, and how much he was using. That should get you started with a list of likely suspects for powder.
Powder and primers can very a good bit lot to lot, even if the powder recipe hasn't been changed. I just got a new jug of H-4895, and an extra grain of powder still left me 40fps behind the load from the older jug.
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