The clicker is hard bolt lift and occurs after 4,5 reloads on most brass. It occurs when the brass is not smoothly extracted from the chamber and it pops loose. It happens at the top of the bolt stroke. The reason it happens is the chamber and dies are so close in tolerance that the brass is not resized enough when reloading. Do a search on here and you will find some very detailed threads. This way we won't derail this OPs thread. Here is one below.
I think my decision between PRC and SM may have just been made ... Worst case scenario is firing actual 300 PRC ammo in the SM ... the SM will allow me to 'download' to lower pressure and get same velocity as the PRC ... but with better brass life and have the tank available for higher if ever...
www.longrangehunting.com