Concerning what's being sold as accuracy kits, I've been doing some testing. First, I clamped a Ruger Mark IV Competition Target in this rest, with all factory parts installed as arrived:

I fired 50 rounds, five magazines full of CCI Standard, and recorded the accuracy.
Next, I installed what was sold to me as an "Accuracy Kit", and again set the Ruger Mark IV Competition Target pistol in my Ransom Rest and shot 50 of the very same lot of CCI Standard velocity ammunition. Accuracy was almost persactly the same as before the kit install. Here's the kit:

♣ #1 Ruger Mark II Light Hammer Get a bit faster "lock-time" Minimal aid for accuracy

♣ #2 Trigger adjustable for pre and over-travel. Adjustments just provide the trigger with minimal movement

♣ #3 Trigger Plunger and Spring. These parts lift the front end of the disconnector up and off the sear. This disconnector is the heaviest of all that I've weighed. The trigger plunger spring must lift this heavier disconnector from one end only, with all the weight involved forward of the spring and plunger.

♣ #4 Sear Spring. From all of my measurements, this spring is so close to being the same as the Ruger factory sear spring that I found very little difference to offer much improvement.

♣ #5 Target sear. If anything, this is the KEY component involved with this accuracy kit. It will reduce trigger pull to a very safe 2½ to 3 pounds, but I achieved no substantial improvement in what the kit was perceived to provide. Accuracy.

♣ #6 Disconnector. This is a steel, machined part. It's sole purpose is to connect the trigger to the sear for release and then re-set. It is heavier than the factory disconnector by almost 37%.

♣ #7 The hammer bushing. This part rides inside the hammer and the right end is captured in the disconnector window at the rear. As the trigger is pulled the bottom piece on the disconnector leaves the sear, and then the right end of the hammer bushing contains the disconnector from flying upward.

The two thin spacers are not meant to provide any accuracy improvement but only fill any voids between the bushing and contain side to side movement if needed.

So, not too many of these parts can, or will, provide much for accuracy improvement, or so I've found. What part does provide the most improvement, is the target sear. It would be terrific if we could only buy the sear, but that's not in the works at this point in time. What would be a considerable gain, is if the $150.00 + cost with shipping could get more palatable with a kit that ONLY helped with creating a much better, lighter and smoother trigger weight and pull could be acquired.
I know someone who is getting very close to achieving that end, and much more affordable.