Sorry to hear of your problems. Let's get some more info out here so we can be of more help.
Does your rifle have a light trigger pull? Very little creep? If so the sear ledge may not be large enough to safely retain the hammer after firing.
Are the springs strong on the trigger and hammer?
Have there been any double-fires?
With the lower separated, try cocking the hammer by hand. Now grab it from above and lift, to try to get it to fall w/o pulling the trigger, aka pushoff.
If the hammer can be pried up and made to drop, then the sear engagement angle has been altered and the hammer is following the carrier down. Replace the hammer or FCG if this is the case.
When you release the trigger from the rearward (fire) position to allow it to reset, does the reset take place near the end of the trigger pull (soon after it begins going fwd) or near the end of the trip back to resting position? This will give clues as to the state of this rifle's disconnector timing.
Chances are, your trigger is out of spec. Could be the hammer itself, but I'm putting my green on the trigger nose being out of spec, coupled with a disconnector that needs adjusted to function better in this weapon.
Good luck; hope this helps...