What I'm gonna do here is share what I can. I am going to do my trigger job on the Smith and Wesson M&P 340 357, the Scandium Framed 357. I call it the Beast.
You'd understand if you shot it with full house 357 loads. But it carries easy and is there if you need it. I mentioned it in Bugs' post on his Apex Trigger Job, we couldn't figure out how to get the grips off, it takes a special tool. 
This morning, I made some wedges in the workshop, and the grips slid right off. I have ordered some nice wood grips from Brownell's and they will be here Saturday, the factory Hogues won't go back on.
Let's get started. Here is the Beast... note there are no screws visible. What? How do the dang grips come off.
You drive the wedges up beside the bottom positioning pins in the frame far enough to raise the grips free of them, and they slide off easy as pie.
I put the wedges in a ziplock with the grips and put them in my goodie box in the loading room with all the other goodies. This includes the OEM parts from both trigger jobs using the Apex Kits.So, getting started we come across the first real tip from my Rabbi. Smith recommends all screws go back in the frame in their original location. The first screw out, cut a groove across the bottom, you know, like the number one. First Screw, upper left corner. Every Pistol he worked on in the Department he did this. Offers would come in and say, "Gee Sarge, this thing all the sudden doesn't have the trigger it used to." He'd asked if they took off the side plate. "Oh no Sarge, I'd never do that, it's against regs." Pull that first screw and he'd know. Take a look at the top edge of my bench Cutting board. Note the three depressions I cut there. Coincidence that there are three screws and three holes? Note that screw #3 has a spring loaded bearing in it, which holds the cylinder in the frame when it's in place. So, you mark #1, #3 is different, and #2 is plain... Simple. Now the first thing you do when you take the side plate off is lay it right along side the revolver and compare the two. Look for drag marks and see if you can tell where they come from. Look at this one. Drag marks are present on the hammer and the rebound slide. You can decide if they need to be addressed or not. Rather than the paper clip others use, my Rabbi suggests using a properly sized punch. More control with the thicker handle, and never a chance it will fail.
I was shown a lot more than I did to this piece. Without supervision over my shoulder, I elected NOT to use many of the steps I was taught at this time. Better safe than sorry, however I did use an arkansas stone to touch, lightly, several of the drag areas and to remove ONLY the roughness on the three bearing faces of the rebound slide. I also polished the rebounds slide's faces with crocus cloth, NOT sandpaper of any grade. You might also note that I touched up the areas on the hammer that had been rubbing on the frame and the sideplate.
Look closely at the sideplate. I kissed the sideplate with the stone as I had been shown. Then I polished the sideplate on the crocus cloth. There were a number of other things that I could have done here, but I didn't feel comfortable in doing them, I didn't feel I had the skills with just the one afternoon having a master show me all the neat things that HE would do. Keeping in mind that if you screw up a part, a competent gunsmith can replace the part, carefully fitting it in your gun and doing a full trigger job at the same time..... remember that you should stay within your skill levels.
That gunsmith will be laughing all the way to the bank.
I know, I have several friends who ARE master gunsmiths, building competition guns. I once asked one if amateur gunhackers bothered him. "No, not at all." He laughed. "They insure my lathe stays running, I get plenty of business for the bluing tanks, and I get to fit plenty of new stocks after they try to put slings on." 
My trigger job? It didn't turn out as well as the supervised job I did under the Rabbi... it wasn't between 8 and 9 pounds.
But, the Beast's trigger was between 13 and 14 pounds the last time I had it checked years ago, and I measured it with the new trigger pull gauge. Five tests... five readings of 9- 1/4 pounds. Not bad for a BrokenOlArmorer. 
