Most of us have done this a hundred thousand times...but we don't really think about it probably.../ and I'll discuss Browning Over Unders...
I store my guns in the safe...with the firing pins uncocked....(so after cleaning - you put the gun together - and before you put the gun away / you dry fire both barrels ) and relieve the pressure off the springs. But what it also means, is the cocking lever - that is at the bottom of the receiver - when you look inside it ...rests firmly at the bottom of the receiver ( it does not move up and down freely ) because the cocking lever will only move up and down freely - when the firing pins are cocked.
So I take the gun out of the safe ( its fully assembled ) but firing pins are not cocked.
I take it apart by removing forend...then I move the locking lever to the side and remove the barrels ( firing pins are still not cocked ) ...separate the barrels from receiver....put the forend on the barrels and put that in the breakdown carry case ...and put the receiver and stock in the carry case ( firing pins are still not cocked ).
Get to range ...and assemble the gun ...firing pins are still not cocked.
Cocking the firing pins only happens when the gun is fully assembled - you move the locking lever - you rotate the barrels down - and the firing pins are cocked by that action / when the gun is fully assembled at the bottom of that rotating the barrels downward. The gun is left open ...and you move around the gun club ( firing pins are now cocked).
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If you leave the firing pins cocked - which is what I think happened to Dreaming...the cocking lever moves up and down / which is ok, you can get under it for cleaning, etc.....but if that cocking lever is moving easily - you have to be careful when you mount the barrels to the receiver...because the cocking lever needs to be flat - and down - when the barrels go on, or it will bind. When I put the barrels on ...I hold the stock and receiver in my hand parallel to the ground ...but if your short..(like Dreaming ...) ...and you point the receiver up toward the sky and mount the barrels ....that cocking lever may move...and bind.../ ( just kidding about the short jokes...) sort of....
/ don't want to let the barrels drag in the gravel as you go to mount them on the receiver...