Point Of Impact Adjustments on Target Shotguns

Variable settings on the front of the rib and the Stock Comb (sighting eye) height will change the Point Of Impact. Lowering the rib front and raising the stock comb (sighting eye) will raise the POI. The reverse will lower the POI. When I shoulder my 33 1/2” Perazzi my sighting eye is approx. 4 1/2” behind the rear face of the Perazzi barrel.
If so,
— An elevation change of the front of the rib 0f .0257” will change the POI 1” @ 40 yds.
— An elevation change of the stock comb (sighting eye) of .0264” will change the POI 1” @
40 yds.
NOTE: Basically a change of .026” of the rib or the comb will change the POI 1” @ 40 yds.

POI changes of the rib and the comb are additive, therefore, if you lower the front rib and then
raise the stock comb (sighting eye) to achieve the same sight picture, the total
POI total change will be the sum created by the two changes.

Incidentally, the rib elevation change on a Perazzi barrel from one notch to the adjacent notch is approx. .045”, a 1.7” change of the POI AT 40 yds.