Wolfe sells a "shooters pak" for the 2011 and later model SP-101 .22LR. It includes a lighter (8 lbs versus 10 lbs) trigger return spring as well as reduced power hammer springs (13, 14 and 15 pounds versus the 16 pound factory spring).
The bulk of the trigger pull reduction will come from the replacement of the trigger return spring, with very little additional benefit from a lighter hammer spring. The lighter hammer springs will potentially cause light strikes, so you'll want to try each one and go with the one that gives you 100% reliability with your ammo. Or just install the 15 pound spring and be done with it, as the improvements in the trigger pull with the 13 and 14 pound springs are not noticeable.
The hammer spring isn't hard to replace, but you need to know what you are doing to replace the trigger return spring. There's another spring in there that you'll launch across the room if you are not careful and/or don't know what you are doing. Googling Sp 101 spring replacement on Youtube should result in 1 or more videos that will get you up to speed.
The end result will be a usable trigger. Like all Ruger revolver triggers, it's much more mechanical feeling than a S&W, and the sparring replacement won't change that, but it will be lighter and easier to shoot.
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All that said, I've had two SP101 .22 LR. The first went back to Ruger twice before they replaced it. It had truly horrible leading issues and Ruger ultimately determined it was "non-repairable". I eventually got a new one to replace it, but it took 5 months start to finish as they replaced it out of their next production run, rather than having a whole saler send me one. I wasn't real impressed.
The replacement was reliable enough and didn't have any leading issues, but accuracy was marginal. I traded it on an S&W Model 17 and have never regretted it.
