The shapes were also chosen on purpose. Take for example the UFO. The kill size is non standard, so is the distance to the hinge. the idea is to place that target at just under 40 yards as it will bracket (kill and hinge) at exactly 45 yards. Nasty i know......but it works as many shooters go over the top for a doughnut
The Emley moor towers are diliked by the FT shooters as the wind at 55yards can easily make you miss the metal totally giving no help to the shooter as you cannot see where the pellet missed.