A Wilson drop in trigger may simply drop in and require no modification. However, if it binds in the trigger channel, you will need to file the offending portion of the trigger. The amount of filing is usually minimal.
First, disassemble your 1911. Then, drop the new trigger into the trigger channel and check for smooth movement. If you feel any binding, you can use a permanent magic marker, such as a Sharpie, to color the contact surfaces of the trigger, place it back in the channel, move it back and forth several times, remove the trigger and look for areas where the ink has been rubbed off. File those areas.
Once the trigger moves smoothly in the channel, reassemble your 1911. You will need to adjust the over travel stop screw. Adjust the screw so that pulling the trigger fully releases the hammer and the hammer falls freely and does not contact the half-cock notch. Once the set screw is adjusted, put a little blue Locktite on it so it does not move.
That's about it. It is not too difficult and this was the first major 1911 upgrade project I ever did.
By the way, looks like I beat 1911Tuner to this one, guess he was still eating those worms!
