I've got a vintage Parker with a LOP of 13 3/4"
It's a 20 gauge with long barrels and tight chokes.
I've used a Galco slip-on pad to add 1/2" to my LOP but the shaped Silvers pad doesn't sit quite right inside the Galco.
Last evening, I slipped on a Galco barrel guard which sits mostly in front of the forend and when the gun is mounted and my left hand is half on the forend and half on the Galco barrel guard, it feels as if my LOP has been increased by at least 1/2" or more.

With no change between my right arm, my shoulder, the end of my Silvers pad, my trigger finger and the DT's of my gun, what's going on?
Thanks