Do a Google search for "Ruger MK bolt racker," and you should see some options. From there, you could "rabbit hole" all day!
Some similar (or at least related!) accessory options:
I think this one might be the most common(?), but of course the link won't show the "preview," like some ofthe links!
Other options include:
Ruger MkIII/MK IV Bolt Racker The MK Machining Ruger MkIII/MK IV Bolt Racker allows for easy bolt racking on your Ruger Mk III or Mk IV pistol. Available in the following styles Left/Right Handle Winged Handle Loop Handle Due to varying bolt to receiver tolerances across many thousands of...
www.mkmachining.com
Slightly different idea:
Our Bolt Racker allows for effortless cocking of your pistol. Lightweight aircraft grade aluminum Easy to install Can be mounted for right or left handed shooters Flat black anodized finish 3 types for all variations of production Choose the correct type for your pistol.
majesticarms.com
Check out the BROWNELLS available Online at Brownells Today and many more Handgun Slides & Parts products are available in our Gun Parts Department.
www.brownells.com
I've never seen the need for one, but it's always interesting to see what people can invent!
Be aware that there are at least two different bolt "ear" designs out there. I'm a "MK II guy," but even mine have two different bolt ear designs- "squared" or "tapered." I don't know what the MK III and MK IV have, for bolt ears.