The stock trigger on my Sig p938, and indeed all p938s, was polymer. Being that it was the only plastic part on the gun, I decided to swap it out for a stainless steel one. I came across Glenn at PartsProduction who had some stainless triggers made up. I found that his website had a mistake on the link to his email address. The email address shown is different from the one that comes up in your email if you click the link, so just type the email address that you see on the page to get in touch with him. Im not going to put his email address here so I dont contribute to his spam folder, but you can find it on his website here http://www.partsproduction.com/Trigger.htm
I watched his video that is linked to on his web page for directions. Its pretty straight forward, but an extra hand would help a bunch. I had to use tape to cover the hole in the trigger to keep the spring from shooting across the room while trying to get the trigger bar in just the right position. I also found that getting the pin out that the trigger pivots on is a real PITA. It is really on there and takes more force then I was expecting to get it out. My pin punch broke while working on this so I ended up using the nail set similar to the one in the video. But due to the tapered end, it cant be used to drive the pin all the way out. I had to finish it off by mounting a allen wrench in a vise and setting the pistol frame on top of it. After a couple whacks with a rubber mallet the pin was out.
This trigger seemed to create a fault with the gun causing a failure to fire after a couple magazines. See update here