What truckernix said.
If the gauge is between the pressure port on the block and the filter you are only measuring how dirty your filter is. The return line from the filter to the block just dumps into the crank case so the only resistance in the lines to cause a pressure reading on the gauge is the filter itself, the dirtier it is the more pressure you will read.
Cap or plug any of the lines between the point where the gauge line comes off and where the filter return line reattaches to the block. Now your gauge is on a dead-end line and will show the pressure that your bearings are seeing.
