Barrel fit up to my old 12 (1974), ready to rock; 1 shot with std hunting 7 1/2s went just at and above the sights at 25yd., Stout! Same POA with new, cheap Rem Slugger went above POA by a couple inches; next shot and ...bummer, repeated light strikes. No transfer bar in this either. Time to tear it down; oh well, it is winter.
Old style, double leg torsion mainspring seems weak, but this gun has been sitting for about 15yrs. now, (no, not cocked). The firing pin retracting spring is a bit stiff, maybe 'dampening the strike' too much?, so I drove out the pin and replaced it with a softer coiled spring from my bins. Also checked the firing pin protrusion, only about .030, so I lightly filed the hammer stop (the frame contact just below the rear of the firing pin; I checked for contact with a thin paper strip 'feeler' while holding forward pressure on the hammer) and got to .035 quickly.
Fired one OK, but still not a very strong indent, next one failed.