I recently picked up a new/old stock DA/SA 9mm P229 with a manufacture date of 2009. The gun came with a mix of machined and MIM parts, including a MIM sear. I purchased a current production DAK kit and a Gray Guns trigger. I currently have the same setup in an 07 P229, which I installed myself with no issues. I have a fair amount of experience with detail stripping SIGs, particularly SIG frames, and I am pretty comfortable with the process.
I also found an new/old stock machined sear (part #1200211), and decided to install that at the same time. When I reassembled the gun, pulling the trigger caused the hammer would go back, but it would not fall. I took the gun apart and put it back together several times, but kept having the same issue. I wasn't sure if it was the Gray Guns trigger at first, but I was able to see that the overtravel wasn't blocking the trigger. Eventually I put the factory MIM sear back in, and that solved the problem. Now the gun functions normally, and the trigger pull is decent. However, on a second strike trigger pull (with the hammer completely down instead of the pre-cocked position), it does take more pressure to reach the "half cock" position where the DAK hammer usually rests than my other DAK guns, and the initial part of the pull is a bit rough. When the hammer reaches the half cock point, or if the slide is cycled so that the hammer starts where it normally would, the trigger pull is comparable to my other DAK guns.
Any ideas as to the issue with the machined sear? The issue is pretty much solved--rock on with the MIM sear, and live fire the gun to ensure there are no issues, but I'm confused as to why the machined sear wouldn't function? SIGs use the same sear for DA/SA guns as the DAK gun, and the gun currently has a DA/SA sear, just a MIM one instead of a machined one. Visually, the sears have virtually no difference, except that the MIM sear has a hollowed area in the side, and a semi-circle cut on the left hand (if installed in the gun) "leg." I'm attaching a picture of two different sears for reference. The sear on the left looks exactly like the MIM sear in my gun. The one on the right is SIMILAR to the machined sear I purchased (i.e. it does not have the semi-circle cutout on the leg), although the picture depicts an SRT sear, and the machined sear that I purchased is NOT an SRT sear--it's a run of the mill machined factory sear.
Anyone encountered any issues like this? Any insight would be appreciated!