A box of FA dummies

This one came un-open, what is the headstamp inside?

I suspect that the “S” in the lot number indicates “steel case”. The most common steel cased .50 caliber FA dummy I have seen over the years is headstamped “F A 4” with the “4” being centered at 6 o’clock. Zinc plated steel with 2 or 3 case holes and a blind primer poket as I recall… they must have made millions of these.