Very glad that I haven't modified my SD9VE. If you look back through the posts on various threads, their is quite a bit of discussion about spring rate and something generally overlooked, pre-load.

In particular I suggest looking at posts by OKFC05, which include analysis of several spring system factors, including a link to the company that makes the S&W springs.

(He has a physics background and is very good at systems analysis. This may cause some folks to skip over his analyses but he does provide a scientific and un-biased analysis of gun actions.)

About those tabs, I finally found them because I wondered where the rear of the spring is held, and it clearly those tabs that metal guide rods seem to attack if there is a hard hit at recoil.