The ring which is cast into the outer perimeter of the head casting splits and breaks off meaning the copper head drops/flies out. We use them to destruction and this is how they go.
good oh I just like them to be honest I only beam bash and I've had a few telling offs for making plates with the ledge hammer and the ball pein hammer ill use the newer one and restore the old one for my own ends at home and if the other one goes walkies at work it can be replaced by the firm then
I have had mine since 17 years old, it needs a new hide but copper is ok(ish) although slightly worn one sided where obviously I hit it slightly wrongly(twisted) but they are a great asset , the hide side was used when rewinding motors/armatures and the copper for assembly/dismantle of mechs.
can be used more often than a dead blow I think.Arther
I normally get one copper to two hide. I replace the hide end once, but by the time the second is past it so is the copper.
The head gives way and the edge splits off so it wont hold a new one.
New ones arent expensive, £23 for a number 3.
I tend to use a 3, light enough for delicate assembly, buy hevy enough for knocking back an over folded bit of 6mm plate.