It can be DIY, but put the Dremel down and back away...
A little rouge/simichrome/flitz/pumice paste can do wonders. I suggest removing the FCG parts from the frame, generously apply your polish potion and then free-hand lap the bearing points-as in spin the trigger freely on the trigger pivot pin, etc.
Do not remove any metal with a power tool...at this stage, and do not play with parts geometry yet either, or bend springs. Just artificially wear it in by de-burring it manually. Thoroughly clean and re-lubricate with a synthetic gun lube of your choice, and poof ALL DONE!
Plenty of good vids out there will you show you how to disassemble the P230 .380, but I'll talk you through it if you have difficulty.
SIG pistols of German origin respond tremendously to this technique and you'll have a smoother trigger for sure, without compromising safety or reliability.
Regards from a SIG armorer school grad.