This post is a brief lesson on after market triggers in the tac-15i.
The housing that holds the trigger assembly via 2 pins. Is dimensionally similar in width and heigth to an ar-15 lower. With the 2 pins sharing the same size/spacing relationship to current production ar lower recievers. This allows aftermarket triggers to be installed relativly easy in most circumstances.
The ar style trigger supplied by PSE apears to be a standard OEM trigger as found in most standard ar style recievers. Honing and polishing these triggers is a time consuming and often fruitless endeavor.
I have installed a Jewel ar-15 trigger in one tac-15i and the only modification I had to make was a spacer block in front of the hammer spring to hold the spring "roller" in the forward and down position. On a ar-15 lower the trigger well in not as generous as the tac-15 forward of the trigger housing. This is why the spacer is needed, to keep the proper tension on the spring by holding the stationary arm of the spring in a tensioned position. On the tac-15 the extra room allows the spring to unload by not retaining it into it's normal position.
Triggers like the Rock River arms 2 stage match should not need this mod. That triggers return spring works off the bottom of the trigger well and the hammer spring is held by one of the pins and not the front of the trigger well as with the Jewel.
Accessing the trigger well is done by the removal of the 6 allen head socket screws the are located ajacent to the grip when looking at the cross bow in the upside down position. This will split the "upper" from the "Lower".