I've noted the other posters here are all more than likely much much better competitive shooters than I ever was. So my advice is from a guy who was at best a mediocre C class shooter 20 years ago.
The only thing I'm going to stress one last time is the gun has to fit the shooter. The Ruger MK series is a great gun but not the only rimfire that is usable for steel. I don't know if your gun has replaceable grip panels or if something like the Hogue slip on grip would fit or even help but it might be worth a try to get what works best for you.
While at the range if the opportunity comes up try a rental or someone else's rimfire and see how it feels and works with your grip. Something bigger, smaller, more contoured, or at a different angle might help.
Keep on, keeping on.