I am asking because I never had a problem with it, however this is now the second generation of hens that have shown this very badly. I brought in a completely unrelated cockerel last year, but his daughters this year do exactly the same thing... they were not reared with their parent stock, so couldn't have learnt it from them.
They have a large (about 15 by 10m or so) enclosure, with a lot of rough grass in it, are laying well, get layers pellets (more or less ad lib) and a handful of corn in the afternoon. Grit is available. They are not crowded in their house, but aren't very good at perching o/night. They are Copper Marans (mostly, but I do get the odd throwback to either LSx or RIR), but are bascially black with a bit brown speckling on their necks and chest. They hatched early July 2015, started laying late Dec 15. Not running with cockerel atm.
We lost one fairly early on as I just hadn't spotted it, and I had to remove one hen badly vent-pecked (but she is laying fine again) earlier in the week, and now have just had to rescue another one (who promptly bullied the previous single one, but I have run out of emergency runs, so they have to sort it out amongst themselves)... It isn't just one that is doing the pecking, they all go after the pecked hen...
Anyone got any method to stop this? Or do I just have to start with completely new stock?