In the one photo where it looks to be about half cock, it looks like the bottom of the hammer is interfering with the edge of the trigger, just where the hammer foot inserts into the u shape of the trigger. If that is the case, do not file or stone either part!!! It will only give you a short throw feel and mess up the entire action.

Don't ask how I know this!!! I would guess you need a new sear installed as that one is worn, BUT, like Toolguy said, it is difficult to determine cause without gun in hand and careful observation. Especially from pictures.

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Richard Gillespie
FBINA 102