That was an issue with all the Ruger .22 pistols from the Standard model which came out in 1949 through the Mark 3. They redesigned the pistol with the Mark 4 series and this is no longer an issue with the Ruger .22 pistols. There was a technique to taking them apart and reassembling them and they were a PITA in that regard.I had a Mark II. it was the hardest pistol to take apart that I ever owned.
Those are nice grips on your 22/45 Square Target. A friend of mine bought an earlier series 22/45 that had fake grip panels molded into the frame. He hated those so much that he milled them off the frame and replaced them with a set of double diamond grips for a 1911.