Quoted:
It appears that my disconnector is not functioning correctly. As long as I maintain pressure on the trigger the hammer will not reset. If I am not mistaken that means the gun would runaway if I tried to fire it. Is that correct? How do I get the disconnector functional?
View Quote
As long as you maintain pressure on the trigger, the hammer SHOULD NOT reset, that's the whole purpose of the disconnector.
Or do you mean the hammer just returns to forward/fire?
(do not let the hammer slam unrestrained into the lower receiver during the following if you're doing it with just the lower)
Cock hammer
Pull trigger - hammer should fall - HOLD TRIGGER TO THE REAR
Recock hammer - hammer should click onto and be retained by the disconnector
Release trigger - hammer should click forward a small amount and now be held by the trigger
Engage safety
Pull trigger - hammer should not fall
If the hammer is not being restrained by the disconnector, then yes you have a problem.
One common issue when people assemble lowers is swapping the bolt catch and disconnector springs. If you put a bolt catch spring in the trigger, generally the disconnector will not work right. Another common problem is putting a disconnector spring in upside down, so that the flared part is outside the trigger - the flared part should get pushed down into the trigger.
With the hammer forward, push back on the disconnector, it should be free to move back and forth under positive spring pressure.
Or you could have a broken or out of spec disconnector and/or hammer. Do you have any spares that you could try swapping those parts? Could also have an out of spec lower receiver such that the parts do not have the right geometry to function correctly.
Quoted:
If your Grip Screw is not standard (too long), then you could also run into a similar problem, by the grip screw pressing on the trigger assembly.
View Quote
Something extending into the receiver from the grip screw hole will act to pull the trigger, by pressing upward on the tail of the trigger.
Some use a set screw in the grip screw hole just for this purpose, as a takeup adjustment. Using a setscrew in this manner allow removal of excess takeup to the point of engagement with the safety. There are also lower receivers on the market with a separate screw for this function.