With just a few exceptions due to the design of the lock (double shotguns) or interference problems with rimfires (some modern rimfires are designed so the firing pin will not strike the breechface, eliminating the peening/broken firing pin problems associated with dryfiring rimfires), dryfiring will cause no harm to a weapon. If it did, not a single service rifle in the Marine Corps inventory would function, because dryfiring (and LOTS of it) is a standard practice during "snap-in" week for rifle qual. We also extensively dryfired the M9 (Beretta 92F) handguns during pistol qual, too. I dry fire all my rifles and pistols for practice learning trigger control. I also never store a firearm with the weapon c0cked, for no other reason then personal preference.
Mike