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Two Quick, Worthwhile Ruger Mk IV Pellet Pistol Upgrades

Today we’ll look at two simple, worthwhile Ruger Mk IV Pellet Pistol upgrades.

In February 2022, the HAM Team reviewed the Ruger Mark IV airgun. It earned a Gold Award for it’s performance and is a great little pistol for less than $50. But there’s some problems that spoil the overall performance of the gun. Basically, the issues arise from the unbelievably-heavy trigger pull weight.

The average trigger pull weight recorded on test was 10 Lbs 8 Oz. Ouch!!!!

Worse than that, individual readings varied from a low of 9 Lb 13 Oz, up to a high of 11 Lbs 8 Oz. That’s a variation of approaching 2 Lbs in pull weight!

The HAM testers decided to see what could be done to improve the situation and yet not invalidate the gun’s warranty.

Let’s be clear, the real solution here is a lighter trigger spring. We can’t understand why this is not fitted in assembly as it would revolutionize the gun for so many people. It wouldn’t even increase the manufacturing cost…

However making such a replacement is complex – HAM Tester Doug Wall has done it – and cannot be recommended to the average owner.

So what can be done?

Well, the sad effects of the heavy trigger can be compensated – to some effect – by making the gun heavier. The airgun weighs-in at 1 Lb 6 Oz. The rimfire weighs 2 Lbs 14 Oz. So, our airgun is about half the weight of the powder burner.

Making the pistol heavier will make the overly-heavy trigger feel a little less objectionable. Fortunately this is easy to do.

The pistol grip side plates can easily be removed by unscrewing the socket head setscrews holding them in place. Having removed one side plate, the “honeycomb” structure of the pistol grip can be seen – complete with a lot of air apace!

Obviously it’s easy to increase the gun’s weight by simply filling those spaces with a dense material. Lead is ideal. Doug Wall had some lead shot available and that worked perfectly. Stephen Archer used some old “junk” .177 pellets to fill the spaces in the second gun we have here. That worked too, as we can see below.

Ruger Mk IV Pellet Pistol Upgrades

Filled with pellets, the gun weighs-in at 1 Lb 10 Oz. Adding that extra 4 Oz of weight improves the feel, balance and handling of the pistol. It also makes that trigger pull FEEL less offensive. Doug’s lead shot did even better…

OK so what about the trigger itself?

As we said, without complete disassembly of the gun, it’s very difficult to make a big improvement.

However, it is possible to make an incremental improvement, simply with lubrication. But how to get the lubricant to the right place?

Without taking the gun apart, Doug Wall sprayed some WD40 water-resistant silicone lube into the action above and behind the safety.

Ruger Mk IV Pellet Pistol Upgrades

He followed this by puffing-in some extra-fine powdered graphite. You’ll find this sold for use on sticking car door locks and similar applications.

The result was impressive!

In Doug’s case, the trigger pull weight was reduced from an average of 10 Lbs 8 Oz to 6 Lb 7 Oz. That’s a 4 Lb improvement, just by adding a little lubricant.

In Stephen’s case, the result was a pull weight reduced from an average 10 Lb 14 Oz to 9 Lb 8 Oz. Far less dramatic, but still an improvement. Maybe Doug had a better aim with the lubricants!

Ruger Mk IV Pellet Pistol Upgrades

So there we are. Two simple, worthwhile Ruger Mk IV Pellet Pistol upgrades that can improve the shootability of your airgun without serious surgery or invalidating the Umarex USA warranty.

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Ruger Mark IV Pellet Pistol 0.177