Introduction
In 2016 I purchased a Ruger KRH-45-4 Redhawk in .45 Colt.  I milled the ejector star to accept .45 ACP cartridges in moon clips (refer to my article Converting a KRH .45 LC Redhawk to Shoot .45LC and .45ACP).  The manual I downloaded from the Ruger web site clearly states that it is ok to dry fire the revolver.  However, in the process of dry firing, something broke inside the revolver.  There was no longer any spring tension on the hammer or trigger.

Repair

My first thought was that the mainspring had broken.  The mainspring provides tension for both the hammer and trigger.  When I disassembled the revolver, I found that the hook at the end of the hammer link had broken off.  This hook attaches to the mainspring lever which applies tension to the mainspring and trigger.

I purchased a replacement hammer link and hammer link pin from Gunpartscorp.com.  I drove out the hammer link pin with a punch, installed the new hammer link, then replaced the pin.

Installing Hammer and Hammer Dog Shims
While the gun was disassembled, I decided to install shims for the hammer and hammer dog to eliminate side-to-side play.  I watched a video on YouTube on how to measure and install hammer and hammer dog shims.  https://www.youtube.com/watch?v=05SG4q6aP2Q

The hammer dog rides against the top of the trigger and causes the hammer to move to the rear when the trigger is pressed in double-action mode (refer to my article Performing an Action Job on a Ruger Redhawk).  This article explains how the Redhawk action works.

Following the instructions in the video I measured the hammer side-to-side play at 0.009”, and the hammer dog side-to-side play at 0.011”.  I subtracted 0.003” from the hammer measurement giving me 0.006”, divided by 2 meant I needed two 0.003” shims.  I subtracted 0.003” from the hammer dog measurement giving me 0.008”, divided by 2 meant I needed two 0.004” shims for the hammer dog.

I purchased the shims from TriggerShims.com.  The online order form allowed me to specify the thickness of shims that I needed.  To install the hammer dog shims, I started the hammer dog pin from one side so it protruded about 0.004” on the inside of the hammer dog groove.  I placed a shim on the pin, installed the hammer dog, then pushed the hammer dog pin just enough to hold the dog in place.  I installed the other shim on the other side of the hammer dog, used a punch to align it with the hole in the hammer dog, then pushed the hammer dog pin through so it fully captured the hammer dog and the two shims.

I followed the tip from the TriggerShims video by placing a thin layer of SFL0 grease on each side of the hammer around the pivot hole, then placed a shim on the grease; one on each side of the hammer.  The grease held the shims in place.  I installed the hammer and the shims stayed in place.  You can use any type of grease to hold the shims in place.

Replacing the Grips

I never liked the rubber grips that came with the gun; they were too large for my hands.  I purchased a set of used Redhawk grips off eBay for a reasonable price.  There were many grips available, but most were not in good shape.  Judging by the photos, this pair looked to be in excellent shape.

The plastic grip panel locater for the rubber grips is two pieces and has small locater pins.  The grip panel locater for the wood grips has large pins and is one piece. 

I removed the rubber grip locator by separating the two halves.  I installed the wood grip locator that I purchased from gunpartscorp.com and installed the grips onto the frame.  I installed the included grip screw and put a drop of Loctite blue on the threads to prevent the screw from loosening under recoil.  The grips fit my hand perfectly, but range time will determine how they feel with +P loads.

Summary

I normally don’t like small, wood grips, but this is a large-frame revolver.  The tips of my finger would barely wrap around the front of the original rubber grips, but now, with the wood grips, I can get a firm hold on the revolver.

I was surprised that the hammer link broke while dry firing, but this was a simple part to replace.  Thankfully, the gun didn’t break when needed in an emergency!