The coefficient of friction on the trap's arm is the primary influence on rotation imparted to the clay target. Machines that have thrown excessive numbers of targets with the same friction material on their arms will NOT impart the same spin as when they were new. I would posit that is irrespective of the friction material used. Some are better than others, may last longer, &c, but all deteriorate eventually as a product of exposure, age, oxidation and use. Single pellet breaks are, IMHO, highly dependant on sufficient spin. The target's composition also affects thier 'breakability' as does their moisture content which can be affected by weather conditions such as temperatures and humidity levels where & how they are stored. I can side easily with Murphy on his remarks; they bear the weight of only a few tens of millions of clay targets thrown and shot at by individuals who were attempting to break them all.
On breaking a higher percentage of 'rabbits' of the sporting clays variety: Do what Churchill advocated when shooting hares from a butt; shoot the ground about 8" to a foot directly below the 'bunny', do not shoot directly at it. Obviously, that technique can only be applied when they are on the ground. Also, use #7.5 shot exclusively for rabbits only because they do not allow #6's. Many of those targets are 1/2" thick.
As an aside, purpose loaded helice ammunition before the rules were changed to 28gram loads differed from the 36gram flyer loads in that they had lower antimony content so the shot was somewhat softer and would expand on the targets [deliver more energy]and NOT penetrate as much of the flyer shot had been observed to do on some targets. I cannot speak on the newer 28gram purpose loaded ammunition.
Interesting thread & discussion, for sure!
