Really, you sent it back so they could use some metal polish? Have you removed the Pig Tail spring at least or used some, Break Free, on the spring to loosen them up a bit?
Granted you can stay on target with the heavier trigger pull by staging the "hammer" but you cannot do it in one quick fluent motion, you have to go slow so you don’t hit low-left, if you are right handed, low right if you are left handed.
If you remove the springs keep them in a little container of sort so you can always replace them if you don't like the performance you get or in case you need to send it back to S&W for serious work, Like if your extractor breaks. This was an example that I have heard so many Glock owners say happens to a Sigma. I am sure it just BS. Nothing has ever gone wrong with mine and I have put mine through absolute Hell.
Quick question on the Ruger GP100. Is it very difficult to switch out the barrels, say from a 4" to a 8", or is it as simple as unscrew and screw back in? I am asking because I would like to use the 4", stock barrel, for just home defense and attach a nice scope and rail system with an 8" barrel, for yotes.
I would just use a rifle but the rounds are kind of pricy just to get some varmint.