Originally Posted by Bill Alexander
Hammer/Trigger groups are "supposed" to be 4140 with between 7 and 10 thou case hardening on the engagement surfaces. This will give about 15 thou on the rest of the surfaces. If you can drill and tap, your already have a problem because the sear will collapse, being too soft for long term wear. The same applies for changing the engagement angles. Unless you can get everything set with 6 thou or less material removal the unit will need rehardening. This can be achieved reasonably quickly and easily with Kasnit powder but the result is somewhat of an unknown and should not be trusted if there is any occasion for lead to be coming back the other way during the use of said trigger.
It was such problems that led me to the design of the tactical trigger. This is a single stage unit that already has the angles and positions set, has adjustment screws built in and the finish of the sear is additionally bearing chromed to provide 72 HRC surfaces that will not corrode or crumble. I match it with a reduced weight hammer but it is designed to run with FA standard units. The latest gen units are machined out of S7 and heat treated as we found this material to be the best available with good toughness, hardness and corrosion resistance even before the chrome.
Bill Alexander