My rule of thumb is that your nose should be 1/2 to 1" away from the base of your thumb, when the gun is properly mounted. Properly mounted means with the butt in the pocket formed just inside of your should muscle. The heel should be about even with the top of your shoulder. It should not be on the shoulder muscle, not out on the upper bicep and not low on the pectoral muscle.
Drop at the heel without knowing the drop at comb is not very complete information. The comb height is what determines where you cheek will be. The usual result of a too-short LOP is getting your nose bumped by your thumb, not getting a chop in the cheek. A cheek chop IMO, is more likely a comb that is so high you have to smash your cheek down on it hard to have a proper view of the rib. It could also be a combination of too much drop causing the gun to rotate up, allowed by too loose a grip with the front hand and heavier than necessary loads in a light gun. It's also possible that you are simply cheeking the gun too tightly. This not uncommon, especially with long-time rifle shooters who think that's what they are supposed to do.
It's quite possible that you'd be better fit with a longer stock but I doubt that LOP is the case of your chopped cheek. JL
