Welcome back to the Rimfire Report! This week we’re going to talk about a home-cooked modification for the Ruger Mk. IV. The Ruger Mark .22LR series of pistols have been a staple in the rimfire community since its introduction in 1949. Offering at first simple design, the series has gone through 9 iterations since then to improve on the platform and bring more variety into the mix. The Ruger Mk IV is the latest of these pistols and it has even solved the complicated disassembly problem that many have groaned over in the past. Today, the Ruger Mk. IV sits atop the list of best rimfire pistols. Even more so in the competition world.
Ruger MK. IV 3d Printed “Bolt Racker”
Over on Reddit, user DarthScience has designed and 3D printed a “bolt racker” for his Ruger Mk. IV. DarthScience uses his Mk. IV in the Steel Challenge, specifically in the Rimfire Pistol Open division. The Rimfire Pistol Open division allows modifications to the pistol such as red dot sights, and muzzle brakes to aide the shooter in cutting down their time.
Basic premise of this project was that I really wanted a bolt racker for my Steel Challenge RFPO gun (Mark IV 22/45). I’m a little wimp, and hated getting my fingers pinched in the stock bolt ears and upper receiver. A bunch of the bolt rackers that I could find online were only available at such that the extended portion was always horizontal ( and I didnt want the Tandemkross “halo” charger). I was looking for one more like a 2011 Open gun style racker that was slightly angled for my large hands and away from my grip.
Design and Cost
DarthScience modeled the bolt racker himself based on some other concepts he’d seen online that uses a nut and screw to secure the bolt racker to the ears of the charging handle. After designing the model, he then used an outside printing house to do the print work for him.
The total cost estimated by DarthScience two to three dollars if printed on your own printer. Using cheap plastic like ABS would bring the cost way down but durability may suffer. DarthScience opted to use a “trough-resin” via SLA printing. Since he didn’t have a printer at the time, he used a 3rd party printing service. The people he used charged him about $13 which obviously includes their margin and operating costs. Even at that price, the piece is still only about a quarter of the cost of a retail aluminum blot racker.
The design was actually inspired by another popular 3D printer IvantheTroll.
Seeing a bunch of other 3D printed ideas, like u/IvantheTroll ‘s awesome work, I was inspired and decided I’d model something up and have it 3d printed to try it out. I borrowed from one design I saw that uses a nut and a set screw to put pressure on the bolt ears to “grab” it.
Projects like DarthScience did show that a little bit of effort can help you out in almost any field. DarthScience said he would test his prototype in a few matches and then make some refinements. As of right now, he says there are a few fitment issues that he wants to work out in the future. He is also considering making his next bolt racker out of aluminum instead of 3D printed plastic.
I think this is a great addition to the Mk. IV. I can see having the piece being made out of the plastic 3D printed material being good enough. It is certainly light and every little bit of weight counts in a steel challenge competition. Being made out of a heavier and more durable material too could have its merits, but it’s expensive. I think what DarthScience has created here is a great way to at least test out the design before making it out of a tougher material. Even better, if you already have a 3D printer, this would be a great inexpensive way to upgrade your rig. I’m glad to see people in the gun world getting into 3D printing.
How do you mod?
What are some of your own homemade rimfire modifications? Do you think 3D printing has a place in the rimfire competition world? As always, let us know down in the comments below. If there are any subjects or interesting topics you want to be discussed in the rimfire report, shoot me a message in the comments! Until then, we’ll see you next week in the next Rimfire Report.
Be sure to drop /u/DarthScience a line if you appreciate his 3D printing work. All photos and information were gleaned from his post on Reddit. A big thanks to DarthScience for letting us write about your cool modifications!
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