I bought a 357 mag SP101 back in July and was surprised at the "glitchy" trigger action. I looked up the MCARBO video that 5-shot referred to above and also ordered their polishing kit and spring/shim kit. When everything was pulled together I took my Chromebook out to my shop and went through the video step by step and did the fluff/buff on my SP101 as shown. I also installed the MCARBO springs (I could not use the shims in my gun). In about 1 hours time I had an SP101 with a much improved trigger action. The DA pull weight only dropped a couple pounds BUT it was MUCH SMOOTHER. The SA pull was reduced significantly and it also now breaks sharply. I was truly surprised at the number of sharp edges, machine marks and burrs inside the guns action.
I was finally able to get the gun to the range a couple weeks ago to do some live fire function testing. I was very happy to see 100% function using some of my 38 spl reloads using Winchester and CCI primers, 2 types of factory 38 spl and 2 types of factory 357 magnum ammo. All primer strikes were very positive in both DA and SA. Now I just need to find the perfect grip that meets my demanding desires.
This is the M*CARBO video:
https://www.youtube.com/watch?v=txbCmzM4v6A