I have a US 60 caliber round that looks like a regular T80 ball round, but with a tinned projectile. The electric-primed cartridge is headstamped * F A * 48. The projectile appears to be tin plated and has a gm jacket with magnetic core (you can see the gm jacket through some scratches on the side and tip). There are three knurled cannelures: one on the projectile’s base cup (crimping), one on the projectile about 7.5 mm ahead of the crimping cannelure, and one on the case neck.
Is this indeed a ball round (T80 or some other designation?), and what is the significance of the projectile plating?
The close-up photo represents the color of the projectile most accurately, at least on my monitor.
Thanks in advance for any help!