The Winchester Model 61 is a slide action rifle chambered for the 22 short, long, long rifle, Winchester RimFire or the 22 Magnum. It has a 24" round or octagon barrel with a tube magazine. The receiver and barrel are blued with a plain pistol grip walnut stock. It was made with a rifled barrel and with a smoothbore for 22 shot. There were 10 different chamber and barrel variations available. All Model 61's are takedown guns. Pre-war rifles have a short slide handle and post war will have a long slide handle. There were approximately 342,000 Model 61's produced between 1932 and 1963. Your gun was made in 1948. The values for post war models are:
excellent-$2000, very good-$1200, good-$800, fair-$450, poor-$250.
Add 50% for single caliber guns, (22 short, 22 shot, WRF)
Add 75% for octagon barreled guns.
I hope this helps you,