So far, I have made the following modifications to my recently-acquired Ruger Mark IV Target, to address what I believe to be its shortcomings. Make no mistake -- this is a great pistol, and a vast improvement over the Mark III.

1. Replaced the "holster-ripper" front sight with a sight from the Ruger Single Six, with the base ground to conform to the Mark IV barrel contour.
2. Removed the magazine disconnector. This is actually an assembly consisting of the hammer, the magazine disconnector itself (which wraps around the hammer), its spring, and the hammer bushing. (The bushing appears to be installed in such a way that it's not easily removable, and it holds the other parts together.) Replaced these parts with a Mark II hammer and bushing. (If you can't find a Mark II hammer, you can do the same thing with a Mark III hammer and Tandemkross bushing.)
3. Replaced the stock sear with a Volquartsen Mark II target sear. This goes a long way toward improving the trigger pull.
4. Replaced the stock trigger with a Clark Custom steel trigger. This required a little fitting. First, the trigger pin hole in the Clark trigger needed just a tiny bit of reaming so that the stock trigger pin would fit. More importantly, I had to do some filing on the frame, at the front of the trigger opening. This is because the Mark IV frame is a one-piece CNC-milled aluminum forging, as compared to the welded-together components of the previous Marks. This difference means that the front inside corners of the trigger opening are rounded, rather than squared. They must be squared off so that the Clark trigger can fit and function correctly. This is a very worthwhile improvement since the stock trigger is very sloppy. In addition, the stock trigger has a nub that engages the magazine. This is totally unnecessary and adversely affects the trigger pull. (The three things that vastly improve the trigger pull are replacement of the trigger, replacement of the sear, and removal of the magazine disconnector.)
5. Removed the little magazine ejector at the base of the grip. This is totally unnecessary once you remove the magazine disconnector.
6. Replaced the magazine release with one from the Mark III. The only difference is that the Mark III release protrudes less. I found that the Mark IV part made it too easy to release the magazine unintentionally.
7. Replaced the stock plastic grips with the laminated wood grips from the Hunter version. This is a vast aesthetic improvement. (Note that the orientation of the medallions on the Mark IV grips is different from that of the previous Marks. They are now perpendicular to the barrel rather than following the slant of the grip.)

An excellent tech post; I reformatted it so I could read it and refer back to it.

I hope you don't mind.

The only differences I would have are in the area of personal preference.
In removing the mag safety and doing a trigger job, I prefer to use a VQ MK II hammer and trigger along with a MK II hammer bushing. Costs a bit more, but I prefer to go that way.
I added an extension to the mag release of my MK III's before they became available. I like a slightly longer mag release. I use slightly thicker grips on mine and I need the longer release, but then I have long mag releases on my 1911's, Glock 20 and CZ-75.
I replaced the rear sight with a VQ Bomar type rear sight.

All these are just personal preference things. Many people could come up with similar lists.

ClemY wrote:



Sure, you can do it that way.

The VQ hammer is a so-called "speed" hammer, with a large hole that lightens the weight. It seems to me that by the same token, it would also lighten the hammer blow (less mass in the hammer). A faster, but lighter, strike. Now, I know that experiments have been done that supposedly prove that the hammer strike is not in fact lighter. Basic physics would seem to contradict that.

The VQ trigger has a different profile than the stock trigger. It's OK, I suppose, once you get used to it.

Incidentally, Brownell's, etc. are showing the Clark trigger as "out of stock" or "discontinued." They can be obtained by calling Clark Custom directly. $30 plus postage.

The one VQ component that I really like is their target sear.

Judas Priest, you have to do that much to a brand new gun.  Looks like Ruger really dropped the ball once again just like with their American pistols.  Good grief.

Well, Ruger is a volume operation. You can't expect them to do much (or any) hand fitting and still keep the price affordable.

The other constraint they have is legal liability concerns. That's why they add features such as magazine disconnectors, loaded-chamber indicators, and an unnecessarily heavy trigger pull.

The out-of-the-box "shortcomings" help the aftermarket cottage industry thrive. Where would Volquartsen, Clark, etc., be if the Ruger product was perfect?

The Ruger Mark pistol, nevertheless, is a great value for the money. It's up to the buyer how much additional effort he wants to put into it.

I disagree.  I hated mine.  It ran like crap, even with CCI Mini-mags, it was an absolute PITA to disassemble, the rear cocking knob sliced my finger open, and the bolt was sticky from the factory.  It's gone now, and good riddance.  Probably my second worst pistol purchase ever.