Trying to understand extraction. Here a lot about primary extaction. So if there's primary is there secondary? My understanding is primary is the cam shape at the back of the reciever that the bolt handle rides across. I.e. My Bighorn or a Rem700. My Bighorn doesn't engage this cam until the bolt handle is way up there. So here's the deal, I get smears marks on my case heads even with mild loads. It seems to me that if the case is even slightly stuck in the camber and the bolt turns without moving back the case will stay stuck and your gonna get smears. So IS the bolt moving back at the start of lift? I realize the case should spring back away from the camber walls after pressure is gone. And if it does spring back why do we need that big ass cam anyway? 40 grains h4350 87 vmax 6 creed. 3150 fps. Smear marks!!!Do make it to complicated as I'll have to throw brain data away to make new space. Mike