Hi, Scollops -
I think you will always get the impression of the hex head screw in a correctly dosed Silvia puck. Although I now use a LM ridgeless double basket, I recall that the "correct" fill of coffee in the Rancilio double basket, at least for me, was when the loose coffee was level with the top of the rim of the basket before tamping.
After tamping, the coffee would be at or just a little above the ridge in the basket.
This dosing always resulted in an impression of the hex head of the screw, but usually no impression, or only a faint impression, of the smooth edge of the screen around the perimeter of the puck.