Chip McCormick Corporation
If you bought a McCormick drop-in match trigger (curved or flat) between May and December of 2007, there may be a serious safety issue with your trigger.
Some of these triggers have problems with the disconnector, causing doubling.
You can return it to McCormick on their dime (see the website) for inspection and repair.
Matt (grumbling as I pull the McCormick trigger out of my rifle)