AR Trigger Sticking in the Back Position

[leadaddict]

I assembled this lower from a RRA LPK into a RRA lower receiver last spring. As soon as I assembled it and was testing functionality I noticed that if I held the trigger back and then pushed the hammer back so that it would engage the disconnector, then when I let go of the trigger the hammer would not immediately release from the disconnector. So the trigger would not reset to the forward position.

Let the troubleshooting begin..

I happened to have had a second LPK from M&A parts handy, so I tried it with a different hammer and disonnector and got the same result. So then I figured I would just try to break it in, so I worked the hammer on and off of the disconnector hundreds of times over a few days. It is now working better, but still doesn't let go at all sometimes or just seems sluggish resetting. Then I took it all apart again and lightly polished the contact surfaces. After this it worked for months without failing. It still seemed slow once in a while though.

Which brings me to today. I had not shot it all winter and I mounted a red dot sight on it today and took it out to try it out. I emptied one 30 magazine and had to push the trigger forward 4 or 5 times to get it to reset.

Any advise on what to look for or what part to change would be helpful. I still have the other LPK if there is something i should try changing. As I said, I did try the other hammer and disconnector.

Thanks in advance for the help!

 

[navyretired 1]

By just taking the lower off the the upper and watching the hand-off from the disconnecter to trigger you should be able to see why it's hanging up.
Are they MIM parts and are all the ingagement angles straight and true.
When the hand-off happens it should clear disconnector and the trigger catches hammer immedietley. It sounds like your timing for hand-off is to close and not releasing.

 

[leadaddict]

Yes, from the very start I've been able to see that the hammer is being held too long by the disconnecter. What I don't understand is why. Is there too much tension coming from the disconnecter spring? Is there not enough force coming from the trigger spring? Something else? Is there any way to tell? It doesn't seem to be that common of a problem as my searches haven't found many discussions of it.