The police connection, that multi-space speedloader tray, and the leftover lead residue on the cylinders tells me that the previous owner was possibly a high-volume PPC (Police Pistol Combat) target shooter. That means the guns were probably fired quite a bit, but with rather mild .38 Special-class target loads. Make sure you give each chamber in the cylinder a GOOD scrubbing with a brand-new bronze bore brush and plenty of solvent, to get as much crud out of there before you shoot any magnum ammo. In guns of this type, the .38 target loads would often leave a visible ring of crud built-up at the front of each chamber, and if you shoot any magnums, the empty cases might be very hard to extract, as they will stick to this crud VERY tightly. In extreme cases, large amounts of this build-up can interfere with the release of the bullet in the longer magnum casing, boosting pressures to a dangerous level at the moment of firing.
Clean 'em good and you'll be okay.
"Placement is power" -- seen in an article by Stephen A. Camp
(RIP, Mr. Camp; you will be remembered, and missed)