1860 Trigger Problem

[sail32]

I am having a trigger problem with a 1964 Armi San Paolo revolver.

A light touch of the trigger drops the hammer to half cock from full cock.

A good pull on the trigger will fire the revolver from full cock.

Suggestions ?

Thank you !

[Coffinmaker]

Your description is ........ Confusing.  Are you saying the guns fired from half-cock???  Or, if you lightly touch it, it just drops the hammer into the half-cock notch??
Anyway, the Single Action is not designed to have A really light trigger pull.  I would guess, if you pulled the gun apart, you would find the trigger sear is A.  Badly worn.  B.  Rounded over at manufacture.  Either way, the trigger sear would need to be recut and hardened.
You may also find the full cock ledge on the hammer is worn.  If so, the ledge would need to be corrected and re-hardened.
It may be a combination of both.
You should also do the "pull hammer forward real hard" test.  You should NOT be able to pull the hammer forward off the trigger sear.
The Single Action was actually designed to function correctly with a 4 - 5 lb trigger pull.  The trigger can be adjusted to function correctly with a lighter pull, but, and a BIG but, the angle of the dangle relationship of hammer ledge and trigger sear must be correct.
It's not a kitchen table job and is best done with a special jig.

Coffinmaker

[sail32]

Thanks Coffinmaker.

I made the question corrections.

I was thinking that the problem may have been something simple like the trigger bolt spring or a loose main spring.

Yesterday I picked up a Spanish Santa Barbra 1858 Remington so I should have one cap and ball that works properly.

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[rifle]

There could be spring problems. These guns are part of the curse of fate and Lady Luck  with her fickle finger getting shoved into the wrong places.
Sometimes there can be several symptoms causing one problem.

The advise given so far is good. You gotta know what yer doing messing with triggers because of the safety issues.

These guns can have a target trigger put to them but......the trigger will often make contact with the hammer and the half cock notch on that tumbler. A target type trigger needs the half cock catch rounded over(just right) at the tip sos the trigger can make contact but..the trigger rides over it with no damage to the half cock or the trigger tip and no impede of the hammer. If you want a target type trigger in the two-three lbs range and don't have the expertise to do it right then find a gunsmith that can do it.....or fix the trigger as it should be with a heavier pull fer safety concerns.

Anywhoooo....I'd shoot the new gun and leave the older one to be fixed before shooting it.