Traded into one of these today. Caliber is 6mm Remington. Pretty slick rifle for a 1978 model.Blueing is perfect and the stock is close with nice typical Ruger wood. Accuracy reviews are hit and miss or so it seems. Best I can tell without doing the tight patch down the bore, its a 9 twist. I am not expecting bughole groups but hope it will make a nice deer/varmint rifle. Just liked the looks of this rifle so I figured I'd give it a try.