I have owned several Harrington and Richardson Handi rifles over the years and have always found them quite accurate. However, I have just acquired one in 308 with a bull barrel and it's terrible! I have tried several bullet weight and brands and it won't group under 5 inches. Checked all the basics, rings and bases for tightness and using a Caldwell bench view to secure rifle while shooting. The barrel crown looks good but I am suspecting that's the problem. Any suggestions?