I know that some don't look at the classifieds... so....
I use to own the SIGMA SW40F and had just purchaced a rod/spring assembly.
As you know these are plastic and you need to replace on occasion.
with that said... I have a NEW ONE.... for sale...
cheaper than you can buy online from the cheapest supplier...
your call............. check out the classified ad...
(new) S&W(sigma) Recoil Spring Assembly ($10, shipped)