I have acquired a model 650 (marked so on the crane), but the 4 inch barrel says ".22 LONG RIFLE CTG." and the cylinder only accepts .22LR. The barrel front sight has a green implant also, not red. Serial num ACC2002. Great tight lockup on all 6 cylinders. Good trigger pull on single action, heavy on doubIe. I can't find any mention of a Model 650 marked for and accepting only 22LR. I thought I was getting a .22MRF. Is this a unique variant or simply a modified gun? Your thoughts?