Many British boxlocks will not accept the forend without cocking the tumblers.
I understand that many people do this but IMHO I really don't see why. What damage occurs to a mainspring happens when the lock is discharged, not while kept cocked. Sure, springs can settle if overstressed or poorly tempered but in all my years restoring shotguns, I have only ever had to replace one mainspring due to weakness (and it was a poor replacement) but plenty of times from one too many discharges.
Furthermore, with an ejector, it will fire unnecessarily on opening, either throwing the snapcaps (which I don't like being stored in the chambers anyway) into a dark corner of the room or requiring you to place a guarding hand over the breech.
I'm a simple soul and react badly to shocks first thing in the morning!
Everyone to their own I guess!