Got lucky a while back; was given a Long Branch No.4 Mk.1 with an adjustible Parker Hale flip-up rear sight that replaced the original sight.
First time out on the range during our High Power Rifle shoot, it was shooting like a shotgun, all over the range. That was before I checked it out properly.
Fortunately, like all mature ladies after some proper attention she turned out to be realy acurate.