I've not long been reloading and am finding that when closeing the bolt (which can be quite difficult) it is marking the case head. Anybody shed some light on this. Thanks
+1, you may only need to turn your sizing die down a fraction.
I'd be a little concerned by both facts. Stiff bolt on closing indicates case sizing issues for one. Marked brass, if it is after firing, is a good sign of excess pressure from your load recipe. Tell us more, with pictures if you can.