That was my thought as well, that they were cast that shape for a purpose. No hole to attach anything, and they are solid. Oh well, into the mystery bin they go for some other day I reckon.Interesting shape that seems to be cast in rather than the ends rounded over from using them to hit something. My guess is some type of counterweight. Is there a hole down the center? The shape makes me think they had a mechanical purpose. The number could be a part number as well as an alloy number. Could be there were other sizes with different numbers.
Those that I've seen up close , real functional pieces , had brass cups with the chain fittings there it's been a long time ago . My wood shop teacher was building an all wood grandfather clock .Clock weights would have some simple and secure means to connect to a chain or cable.