Ar double fires/safety functioning improperly

[Hooverfb]

So trying to remember which part handles the safety/ fire control group for the ar15. When uncocked, the safety can (with pressure) be moved to the safe position. I checked this after my buddy was shooting and I thought I heard it double firing. I know that's a sign that spring is broken, just cant remember its name.

I know it's a spring in the trigger as I triple checked it when I put it together, and I've shot it without issue for a number of trips, so it must have recently broke. Would that be the hammer spring? Or I guess if the trigger lob is worn down a bit.

When the safety moves and decocked, it takes pressure to do so but it does move to safe. It's just the parts kit from PSA, no lighter springs etc.

[yotethumper]

Take out the fire control group and inspect it. Trigger spring might be installed backwards.

[Jspradley]

An AR15 should not be able to be put on safe when the hammer is down.

[Raypo]

Is it a drop in trigger? If so, might need a spacer.

[35remington]

Did you try rice?

[Jon B]

Make sure the pins haven't slid in or out. I had this happen on one. Replaced with anti-walk pins and problem solved.

[Hooverfb]

It's the original trigger group, function tested multiple times before ever firing that it could not be put into safe when not cocked. Worked fine for several trips before this occurred. I'll check the pins as mentioned when I get home. No drop in trigger.