Chip McCormick single-stage drop in trigger and hammer assembly. No cheap tricks or compromises: Full strength music wire springs for fast lock-time & reliable discharge with factory or military ammo. Fully machined tolerances of +/-.001" and through hardened, the S-7 tool steel hammer, trigger, disconnector and pins are made with the highest grade, hardest, longest wearing material available. You won't get this kind of quality, performance and service life with inferior surface hardened cast parts! Housing is 410 stainless steel. Factory tuned for a better than average match grade trigger pull with minimum take-up and over-travel. Typical quality Chip McCormick is famous for! Fits Mil-Spec receivers. Self contained parts slide easily into receiver and pin into position. The easiest, fastest way to get an AR trigger job!

These completely self-contained trigger group assemblies are factory tuned for a super match grade trigger pull with minimum take-up and over travel. The innovative design provides unprecedented control, ergonomics and consistency. Constructed of a stainless steel outer casing and steel internal parts for dependable operation. Pre-set trigger pull is 3 to 3-1/2 lbs. Trigger drops in, but may need to be function checked by a qualified gunsmith. May require minor fitting. Fits Small Pin (.154") AR-15 only.

Quoted:
I have a straight single stage from when they were all the rage a few years ago. Is this model updated? I have heard there were problems with the earlier models. Is there a recall or procedure to get the old ones brought up to speed?