Pre-1913 LCS use the bushings in the face of the breech to contain the firing pin. A small lock screw (brass or copper generally) in the face keeps the bushing from unscrewing.
Use a spanner type screwdriver blade to unscrew the bushing after removeing the lock screw and the firing pin can be removed.
Many times the bushings are cracked from use and dry firing, so they may come out in 2 or more pieces for you.
Post 1913 LCS,, as explained above.
Lefever, the original side plate gun,,separate firing pins in the frame held in place by a set screw accessable from below the breech inside the frame. You have remove the hammer w/ mainspring (Flat V springs) on each side to get at the set screw.
Lefever Nitro Special (Ithaca),, Western Arms (Ithaca,,and Ithaca Flues & NID,,,all use separate firing pins in the breech. Held in place by set screws.
Problem with them is that those set screws are staked heavily into place as a rule and don't want to be easily removed.
Usually it's a 'drill the set screw out' to remove a broken firing pin in one of these. Then retap and replace w/a new set screw.
Plus you need to pull the hammer /w mainspring to get at the firing pin & set screw.
Coil main spring on all of them. The Nitro Special is the toughest to reassemble w/o a jig (home made will do) & drill press to compress and hold the mainspring.
Win 21 the firing pin is integral with the hammer.
You need to pull the hammer(s).