Active scrap/salvage/recycling businesses aren't usually very welcoming. They're busy, dirty, sometimes dangerous places whose owners aren't keen on having civilians onsite. I've had better luck at older, slower, half-dead yards. Here in Canada(esp. Ontario), environmental regulations force old yards to clean-up or close, especially the latter if they're in the way of housing developers. I've had better luck shooting on and around old farms, frankly.