The following information includes all of the Ruger Mark (I,II,III,IV) and 22/45 pistol sears and how your trigger pull can become much more smooth in operation, and reduce pull weight, to 2½ to 3 pounds, safely. Over the years working on these Ruger Mark pistols, I've seen quite a few 'gosh awful' sear faces as done at the factory:



The working face of the factory sear on the left has a pretty nasty lookin' finish, and if you look closely, you can see where the hardened hammer notch shelf has dug into a small area of the face on that sear. This condition will never produce a consistent trigger pull, if that's what an owner would like to experience. Some don't care and are satisfied with however the pistol works, as long as there's noise when the trigger is pulled. And that's fine for them.
I do have a fixture, purchased from Power Custom, whereby I can smooth sear and hammer notch faces, and also create a flatter sear and hammer notch face engagement. Here, as always, everything can be overdone, so, caution along with trial fitting to see how engagement is being maintained:



Using this fixture to polish and correct the face of factory sears is much better than doing the work without the need for it, as I have read where some folks claim they can. I have encountered some of the failed attempts also. For those who just want a "drop-in" sear, you will never go wrong when using the Volquartsen target sear to get your trigger pull much better.