Ruger Mark IV Trigger Kits

Discussion in 'Gunsmithing Forum' started by SGWGunsmith, Jul 3, 2019.

  1. SGWGunsmith

    SGWGunsmith Well-Known Member Supporter

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    Normally, when I get folks that call and ask about installing the so called, "accuracy kits" as sold for the Ruger Mark IV pistols, or even for the previous versions, I don't recommend the purchase of those kits. Here's just one reason why.
    Most all of those kits contain a trigger with a "lighter' trigger plunger spring, that, in use, is supposed to have the rear end of the disconnector, pop up and reset into the sear. Now, being that this plunger spring is at the very front end of the disconnector, it's only reliable if it does it's job thoroughly.
    The disconnector in the most popular "accuracy kit" is made from steel and machined to shape. It is much heavier than the stamped versions, and way more heavier than than the titanium aftermarket disconnect that was once available. The titanium disconnector weighs right around half of what the steel disconnector weighs. So, what does this mean? Try to pick up an 8-foot 2 x 4, just using one end. All the weight is out in front of you, so it's not easy. Similarly, the spring is supposed to lift the disconnector in the same manner. Now, if we provide a spring that's a bit lighter, and a part that needs to be lifted, quite a bit heavier, in proportion. The lighter spring can have a harder time doing it's job. That will cause intermittent failures for the disconnector to engage the sear.
    So, if you do decide to install one of these kits, at least use the factory trigger plunger spring, or if you can find one. a spring that's a bit stronger for the heavier disconnector. The stronger spring has very little affect on your trigger pull weight, if any at all. My Lyman electronic trigger pull gauge can barely detect an increase in pull weight with the heavier spring.
    WHY ALL THE HOOPLA OVER RUGER DISCONNECTORS?

    Some of the bodies, on "Team Whiners", complained that the factory Ruger disconnectors were 'flexing' during trigger pull. Well, I didn't major in physics, but I do know a little bit about how the mechanics involved with the Ruger Mark trigger system does work. The disconnector travels in a linear manner, so if the pull weight is so drastic that the disconnector actually flexes, the trigger pull must be well over 50 pounds. Here's one company's solution:
    [​IMG]
    A thicker, aluminum disconnector, now obsolete due to it's inability to play well with a steel bolt. No complaints concerning flexing for the few 1/8 inch thick disconnectors produced though, just durability issues.
    The next step involves the current steel version:
    [​IMG]
    The black disconnector is what you receive when you buy the accuracy kit. Doesn't seem to flex.
    As a result of trying to make a much better disco to replace the version that Ruger has been using for around 70 years, here's what I've seen and tested:
    [​IMG]
    I could detect no flexing when using any of these disconnectors, but I only wish that the titanium version was still available. That disconnector works terrific in the three Ruger Mark pistols that they are now in.
     
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  2. Mongo

    Mongo Well-Known Member Supporter

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    I don't own a Mark IV, my Mark II has the Volquartzen Trigger (which I installed myself) and IMHO is worth every penny
     
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  3. SGWGunsmith

    SGWGunsmith Well-Known Member Supporter

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    Over the years, I've installed and tested EVERY aftermarket trigger, including one I made and several of the triggers that were used for the AMT Lightning, in Ruger Mark pistols. Lately, I've tried the Majestic Arms Ruger Mark triggers also.
    Not one of those triggers did anything to improve the trigger pull weight, according to the trigger pull measurements I made using a Lyman, electronic trigger pull gage. If the triggers have 'em, pre and over-travel adjustment screws do help shortening the time involved with getting the trigger set back up for the next pull, but that's all they do. No help with reducing "creep" either, as that's a different issue altogether:
    [​IMG]

    The older, Volquartsen "paddle style trigger", discontinued long ago, is one of my favorites:

    [​IMG]

    Unfortunately that triggers face extends beyond each side of the trigger guard and some have claimed, that their trigger has been bumped and the pistol goes off. So, this style trigger is no longer available, unless it is purchased used. Guess some owners of that trigger never got the "memo" concerning the safety on the Ruger Mark pistols working just fine.
     
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