Havin' a Fit
Howdy guys and welcome aboard.
The overhang could be caused by one of several things, or a combination of any. The possibilities are:
Barrel/slide lug dimensional issues.
Lower barrel lug located too far forward relative to slidestop pinhole location.
Slidestop pinhole location.
Lower barrel lug feet thickness, or lug height relative to slidestop pin location.
Overlength barrel hood.
The possible issues noted could be caused by one or more involved parts out of spec...or tolerance stacking by two or more of the parts/areas mentioned...in which each individual part is within spec, but the allowable tolerances in the assembly threw the sub-assembly out of spec.
It could also be a simple cosmetic issue. If...when the pistol is fully assembled...the disconnect will reset correctly and allow the hammer to fall when the trigger is pulled...it's probably cosmetic. During the manufacturing process, the older pistols were often finished at the rear of the frame and slide to correct any slight mismatch as needed. Of course, if they were more than just a bit out of alignment, it indicated that something was wrong inside.
With the gun assembled, engage the thumb safety and look to see if it's well-centered in its triangle-shaped notch...and of course...to see if the hammer will fall when the trigger is pulled. If these two things are noted, it's cosmetic. If not, then the barrel fit will need attention...probably in the lower lug feet...or the barrel will have to be replaced.