Re: AR 15 PACT Gold Trigger update
DD, looking at the pictures, it's apparent that there is a D shaped Clip spring on both the trigger take down pin bushings. Very similar engagement method as the spring in the hammer that holds the Hammer pin (On a standard AR single stage). This should engage the outside groove of the trigger pins.
They look like they are only on one side (Left). Since there is only one outside groove on standard AR trigger pins, the side with the groove should also be on the left.
The best way to install would be to drive the pins in from the right. That way they'll easily get started and won't engage any of the other pin grooves. (If they aren't custom pins.) They should click into place and without any rotational force on them, I'm going to guess they'll stay nice and tight.