Ok guys, I am very comfortable working on mechanical things: guns, engines, not so much the Roomba.

I've got a Tubbs spring set coming for my M1A. Hit me on the finer points of disassembling the trigger group and installing a new trigger spring!
I'm mostly looking for tools needed, and where/when to apply pressure so parts dont go flying across my garage
and any ol' masters' tricks that dont usually get published

You dont need anything more than a punch and your fingers. Its very simple after doing it a time or two
https://www.youtube.com/watch?v=z8YC2WT4sXA

youtube is the answer to everything

great resource

No real fine points about it.  Lean on the upper part of the trigger as close to the pin as you can and punch the pin out.  You'll do just fine.
 



Put a very light dab of the grease on the pins, sides of the trigger, hammer, and safety where they come in contact.  Also the hammer spring and guide.  I brush it on with a solvent brush; almost none is best.









Hardest part is wiggling the trigger guard in and out (if you decide you need to go that far).




 

As long as I got it apart, what parts are worth stoning? If I do that how bad will the rust get?

Deburr:: the process where every last whisker of metal is removed from an edge without actually altering the strength of the part. This generally takes 3-6 light strokes with an oiled  green stone.

DePark:: The process whereby the parkerization on a surface is removed but no metal is removed--that is once the surface becomes smooth, leave the rest of the parkerization on it. Flat surfaces are deParked with a flat stone and oil, 1D curved surfaces are deParked with an oiled  flat stone with finger pressure rolling the stone over the 1D curved surface.

Polish:: The process whereby all of the surface treatment is removed, but as little of the metal as possible is removed.

Both pins should be chucked up in a drill and the center sections deParked, no need to dePark the edges where the pins lock onto the trigger body.

The indent on the hammer where the spring plunger makes contact should be radiused with a round stone, the spring plunger should be polished as a 1D surface.
All edges of the hammer should be deburred. The spring housing should be deParked where it makes contact with the Frame.
The trigger frame should be deParked where the hammer makes contact, and where the trigger makes contact. These are sliding surfaces and can be polished if desired.

The safety should have every surface deburred. The detent on which the safety rides should be deParked and polished. The safety spring should be radiused in this area to make the safety operate smoothly.

The trigger should be deParked where it makes contact with the frame.
All edges of the trigger should be deburred.
The two catching surfaces on the trigger should be deParked as a 1D surface.
The hammer catches on the trigger and sear should be deParked.

The trigger sear and release should be polished with finger pressure with a flat stone and oil. You are not trying to alter the angles or the do anything to the edges. You are simply letting the polished parts of the trigger slide over the corresponding surfaces of the hammer without friction. I did not even touch the hooks on my hammer.

And, while you are in there, make sure the firing pin has been deburred.



Covered in grease, like it should be, no rust will happen.

Improved my M1A:
Tubb's Chrome Silicon OpRod and Hammer Spring set.
Sadlak Solid National Match Spring Guide.
NM front sight
De-burred as prescribed above.

Results:

Thumbnail sized shot group while zero-ing.

Pinging a steel ram at 300m. Standing. Buddy re-created the results. This gun hums! It is my new favorite rifle.