not your usual binding sya, seized piston or sticking handbrake .
all is ok when the drumm is on without the road wheel, when the road wheel is fitted and u start to tighten the brake drum starts to bind, the tighter the nuts.. u guessed it the worse the binding.

I have just changed the wheel bearing but nothing with the brakes was touched. hub nut torqued up as it should be.

any ideas?

thanks to all.
russ

Could be a ridge on the internal drum face