What are the flat rectangular "rails" called on both sides of the grip, up near the top of the open area in the frame, when the grip is removed? Has something to do w/ the trigger I believe. Sorry for cruddy description.
That's the trigger bar.
Here's some directions I borrowed from somewhere else a while back. After using them a bit, I chopped and revised them to suit me better. No guarantee expressed or implied. I'm not sure if the nomenclature is official S&W but the directions work either way.
The Frame
Begin your detailed disassembly by removal of the grips. The grips are held in by a pin which can be pushed out with a punch by hand. Once the grip pin is removed, work the grips off. Don't pry w/a screwdriver. You finesse it off by pushing it towards the back and downwards.
Once the grip is removed, you can remove the hammer strut spring and retaining cup.
Note that the hammer pivot pin is attached to a flat spring that the slide release plunger bears against. This flat spring also serves to hold the pivot pin for the sear. The next step is to use a punch and drive out the sear pivot pin from the right side of the frame to the left. After the sear pivot is removed, remove that flat spring that features the integral hammer pivot pin.
The hammer and hammer strut may now be withdrawn from the top. The ejector and its spring may also be removed at this point from the left side of the frame. On the right side of the frame the disconnector and firing pin safety block lever and the associated coil spring may also be removed. Keep these in order to assist in the reassembly.
Now, use a punch and drive out the trigger pivot pin. This may be done from either side of the frame. The trigger bar may be withdrawn from the rear of the frame by pulling down on the trigger.
Tilt the frame up and the trigger return spring and plunger comes out. Now, remove the trigger from the top of the frame. This is done by rotating it such that the top of it leans towards the front of the frame (imagine if the pivot pin was still in place and you press the trigger. As the trigger goes rearward, the top swings towards the front.
The Slide
Look at the right hand safety and you'll see in the center a tiny hole. Insert a punch and depress the plunger. While the plunger is depressed, push the safety forward towards the muzzle. Withdraw the plunger and slide the right hand side of the safety off.
Now, flip the slide upside down. You'll see two plungers. The one on the right hand side (muzzle away) needs to be depressed. While it's depressed, push in on the firing pin to relieve pressure on the safety barrel (or safety shaft or body of the safety). This allows you to slide the left hand side of the safety out of the left side of the gun.
Pushing down on the same plunger allows you to remove the firing pin and the firing pin spring. You should have a disassembly block (2x4 with a 3/4" hole drilled into it). Locate the extractor pin and place the slide such that the extractor pin is directly over the hole in the disassembly block. Punch out the pin from the bottom of the slide. You can withdraw the extractor and extractor spring. This completes the disassembly of the slide. You don't want to remove the other two plungers because to do so requires removal of the rear sight (and resighting the gun afterwards).
Reassembly
Insert firing pin spring & firing pin into the firing pin channel. You need to depress the firing pin block to do so. When properly installed, the firing pin should clear the tunnel where the safety shaft is. Next, depress the firing pin to insert the safety. You have to finesse it in. The safety will come to a rest and the plunger on the safety has to be depressed before you can push it all the way in. Push on the firing pin safety plunger so as to release the firing pin from its forward position. It should "disappear" from the firing pin hole. Now, insert the right hand safety. Push it until it comes to a stop against the plunger. Depress the plunger and it should slip right in. This completes the reassembly of the slide.
Turning to the frame, insert the trigger first from the top of the frame. Then insert the trigger spring & plunger into the trigger spring & plunger channel of the frame.
You might have to insert the disconnector before the trigger bar, or you might not. Insert the disconnector. The "J" faces towards the rear.
Now, insert the trigger bar. Look at the parts diagram to make sure you don't put it in upside down. The trigger bar helps to position the trigger spring & plunger. Insert the trigger pivot pin to hold these in place.
I put the fame such that the left side faces up. Install the magazine safety plunger spring and then the magazine safety and the other flat bar. The dark metal one goes to the right.
Now, insert the hammer. Put the ejector and spring in and secure them with the hammer pivot pin.
Insert the sear. The "legs" go up since they allow for clearance for the disconnector. Now depress the trigger such that it relieves the pressure on the sear. This allows you to manuever the sear into place such that the sear pivot pin can be inserted into the frame from the right side. Push the hammer pivot pin plate down and hold in place. A light rap with a brass mallet and the sear pivot pin should "snap" into place and be held securely by the hammer pivot pin plate.
Test the action. Insert hammer strut spring and cone. Push grip onto frame and then push grip pin back in.
Reassemble slide onto frame.
Function check should always be done on every gun after it is disassembled and reassembled.
1) Insert empty magazine. Pull on base. Make sure it doesn't come out.
2) Lock slide back. This tests that the slide lock works on empty.
3) Remove magazine. Release slide. This tests that the slide surges forward on its own power.
4) Engage safety. The hammer should decock.
5) Press trigger. The hammer should not move. This means the magazine safety works.
6) Engage manual safety and watch the hammer. It should rotate rearwards slightly. What you're looking for is the shaft of the safety pushes the hammer back and away from the firing pin.
7) Insert magazine. Test the DA trigger.
8) Cock. Test the SA trigger.
Now, you're done.
