It's pretty much as ellenbr said. One of my Merkels (12 ga.) is particularly difficult, action cocked for sure, as well as partially opening the action as the forearm is brought home. Of course lubrication (grease) on the forearm hook is helpful. I've considered having the forearm hook relieved by a gunsmith, but I'll just leave it for my heirs to break in!
Most are "tight" but this one is especially so! Tight as a bank vault to the extreme!
Karl