M9 Trigger at risk of making weight

What spring should I replace if my M9 is at the edge of making weight?

Dewey;

Does your pistol have the factory 20# hammer spring ?
Mine always passed when I received my pistol from Dave.
I even replaced it with the Beretta updated "D" spring(hammer spring).
It is now smoother with the "D" spring but is on the "ragged edge" but passes.
You could purchase a Wolff factory 20# or their next step up is a 22#(just to be sure).
Do not confuse getting the Wolff trigger conversion unit for upping or lowering trigger pull, it is for the trigger return update to replace the tiny factory return spring that is prone to breakage(although it could make a difference in feel ?).
If you do upgrade to the Wolff trigger conversion you have to make sure your pistol has the steel trigger and not the polymer or polymer coated trigger(they are different designs and will not fit with out modification to the trigger).
Easier to just replace your trigger with the steel one from Beretta if doing the conversion.

Hope this helps.
Clarence

Dewey, I have a couple of trigger return springs (Factory and Wolff) that might help.  I have a few mainsprings too.  If you don't get it fixed, just drop me a line and I can drop them off somewhere for you.

Cecil

Dewey, The firing pin block spring can be changed or modified for small adjustments.
Neil

replace the mainspring with a 18-19 from a 1911, that should put it at 4.5 lb