Got this cartridge in some misc auction box. Full Jacket/ round nose. Head
stamped 43 M L. I've never seen on like it. No Greenie to 50bmg, trained
on quads and singles. Any ammo collectors know this one.

At first glance, I would think wood training round, but you said jacketed. Has to be heavier than standard ball. Maybe a spotting rd for a larger gun?

Thats weird.... Are you sure it is "ML"? and not LM? On the international Ammo Assosiation headstamp page, ML gets you "Magyar Löszermuvek RT, Veszprem, Hungary" Which was Nazi occupied in 43..... wonder if it could be some sort of reich weapon, but they tended to wafenamt and/or swastica the bejeesus out of their stuff....

LM would be Lowell, MD and they did load 50BMG in 43....

I almost thought it looked like a proof load, but those have a larger bump near the back, and of course cool red paint.... The profile is almost identical to the bluebird rounds (plastic trainers) I wonder if these were WW2 era training rounds or something....

Strange, and very neat post!

50bmg
.My mistake, with 43 at 6 o'clock L is on right, M on left.