Installed on sig mpx copperhead - Timney Triggers AR PCC Trigger

It was a clean install. You will need to remove the safety roll pin (1/16" punch) and slide the safety out to slip the trigger unit under it. The two set screws can be torqued down until they are snug, then give them an extra 1/8th turn to set them. I will check them at each cleaning to be sure. The set screws will ensure the hammer and trigger pins don't creep, and keep the trigger unit stable. The trigger is very nice, and (although not measured) feels around 2 lbs. It is far better than the stock trigger. This makes a great gun even better.