I also have a Ruger MkIII but only use CCI’s Minimag in it. I was using the regular Remington .22 and it was problematic.
Yeah, their regular stuff is really dirty. I generally shoot their Golden Bullets. Reliable. and the most accurate bulk .22 I’ve found. CCI gets good marks for anything they make...lots of specialty stuff, and kudos for biting the bullet and building expanded production facilities. Are you still Down Under?
Try these sometime. If you ever think you might need a .22 for self defense, these are a good choice.
https://www.cci-ammunition.com/products/detail.aspx?use=2&loadNo=0047