I invested in a good, one-piece .22 cleaning rod several years ago for my AR's. Best $30 I ever spent. I'd say it's right about .20 caliber because it fits down the barrel of the Ruger with room to spare.Hi,
As a heads up, be careful when you go to clean that barrel.
My CZ was so tight, I went to a .20 cal cleaning rod, so as not to hurt the rifling?