Check with the guy you bought the batch of 400 from, to see when he purchased those.
I used those same hooks in some jig heads, and cedar plugs some time ago.
The batch I bought apparently came from a bad batch the factory made for about a year, and quite a few broke.
The latest batch they have out now, is good.....
I no longer use them because of the one bad batch, I dont trust them
But still check the timeframe of when they were purchased..