mx03, if the hammer fired pistol is DAO like my old SIG P239 SAS was, you could cock the hammer back, but it would fall forward without moving the firing pin, not stay cocked - which is the same thing it would do when the slide reciprocated (fall forward).
If the hammer fired pistol were single action, or conventional double action (sometimes called DA/SA), then the hammer would stay in the cocked position when you pulled it back.
SA pistols normally have at least one safety, for cocked and locked carry. Conventional DA pistols will typically have either a decocker, or a combined safety/decocker.
Some guns allow multiple function types. For example, the FN FNX can be carried cocked and locked, with the hammer back and the safety lever up. The FNX can then be shot in SA mode when the lever is lowered to horizontal. BUT, if the lever is pushed below horizontal, the FNX will decock and go into conventional DA mode.
Edit: Other relatively common variants on safety and cocking mechanisms would be those used by the CZ75 pre-B and B models, and the various HK P7 variants.
Edit: On safeties... some block trigger movement; some block hammer or striker movement; some block the firing pin.
Some prevent accidental firing due to premature placement of finger on trigger; some require the trigger be pulled; some protect against inertial movement of firing pin or striker due to an external impact on the weapon.
Last edited by MLeake; May 20, 2013 at 02:47 PM.