Were you getting light primer strikes?
This could be caused by hard primers, a weak mainspring, or both.
One possibility is "gunk" such as cosmoline lodged in the firing-pin channel obstructing the free movement of the firing pin, though with a Feg, I doubt it.
Also, make certain your handgun is well oiled, or friction could cause similar effects. Where the hammer pivots is one area you should inspect.
Good luck.