the comp hammer does two things:
1. repositions the pivot points to reduce effort needed to work the mainspring. this translates to a lighter DA pull.
2. different profile hammer hooks whih are much shorter, reducing the amount of rise in the sear to release the hammer. this results in a short and crisp SA break.
you may not need the comp hammer if you go SAO... the reason i say this is because you won't need the lightened DA pull, you only need to move the sear off the hammer hook. so, with careful hands, you can shorten the hammer hooks on the factory hammer and get the same clean and crisp break as found on the comp hammer.
that said, i'm going to move the comp hammer to my carry 40b and the reprofiled factory hammer to my uspsa shooting 40b, since it's already SAO.
if you get the comp hammer, there are two important things you must know:
1. you will need to modify the safety. to know what i'm talking about, field strip the gun and look at the safety and sear. work the safety on and off. note how the safety will block the sear from moving when engaged. with the comp hammer, the sear sits higher on the hammer, and the safety arm that interferes against the sear will need to be shortened ever so slightly. it's no big deal, just remove very, very little at a time until the engagement just begins to work, then leave it. the safety can be engaged hammer up or down.
2. if you will continue to use DA/SA, i strongly recommend using a 15 or 16 pound mainspring to further lighten the DA pull. there's a mainspring calibration pack that has a 13/15/16 pound mainspring... but here's my experience... with the 13# spring, i got a lot of what i thought were duds. i eventually found by collecting them that i had light strikes. the dud rate was about 1 or 2 per hundred, sometimes more. i switched to the 16# spring, and i never had a dud again.
on the positive cam action:
i believe it's in there as a safety aspect, but in a target type trigger it's less than desirable. to fix this, i changed the angle on the sear face that holds the hammer hook. again, i worked very, very slowly until i got neutral engagement. what this means, is that as the sear lifts off of the hammer, the hammer no longer moves backwards. you must be careful, because you don't want negative engagement, where the hammer moves down as the sear lifts up. this will lead to hammer follow and/or full automatic operation. this is done at your own risk.
