Smith and wesson 629 delux

Maybe you could find steel parts and have them fitted.

I like mine, could use a lighter spring as it is a bit heavy with about 1K into it, at first it felt a bit stagey but it smoothed out nicely by itself. Single action is as crisp as any I have owned, double I really feel the mass of the N frame action.

I recently installed some spring kits in some of my S&W pistols. I'm really happy with the results. Shot my N frame yesterday, as mentioned above the single action was great and I don't think the springs did much for that, but the double action was greatly improved. I also did spring kits in 3 J frames. Wow, what a difference in their double action. One other thing I had done in the past to all of them was to polish the bearing surfaces on the trigger rebound block. I also put just the tiny little fleck of Gunslick gun grease under the block when I reassembled. I could feel the difference in that too.

The triggers on all of my Smiths have never needed a trigger job. I shoot them just fine. If you don't like the weight, change out the springs.

Changing springs is a big help. Get a range of rebound slide springs from Wolff, and see which weight gives the best tradeoff between a good double action pull, and absolutely certain rebound. A ribbed mainspring will help as well, but sometimes produces misfires. Even OEM mainsprings vary by several thousandths; a 325 would only fire reliably with the thickest one in my box.
And there is no harm in cleaning up friction spots on the MIM parts, especially the rebound slide's track in the frame. The rebound slide itself appears to be teflon coated.
I've cleaned up the action on a number of MIM Smiths, but polishing with a fine stone is the plan.
For the single action sear, S&W never wanted that to be polished; the trigger tip could be dulled or sharpened as needed. I have never touched the trigger tip on the MIM guns; the single action was more than good enough.
It is possible to adjust overtravel by changing the length of the stop rod inside the rebound slide spring. You can use cutoff drill shanks, or even finishing nails.
Finally, the original, forged parts were only surface hardened; too energetic polishing would go thru' it. Not really sure about the hardness of MIM parts; they are perhaps homogeneous, unless they are hardened somehow after casting. I understand 'smiths aren't anxious to work on something new.
Moon