If you are reffering to a Winchester model 70 bolt action rifle chambered in 257 roberts,then your serial number indicates that your model 70 rifle was made in the year 1950.
1951
Proofhouse.com has sn information.
With the serial number that you have supplied,your Winchester model 1897 pump action shotgun was made in the year 1910.
Value of 257 Roberts Model 722 Serial No/ 319811
When the bar was first made in 1967,the rifles were not made in 257 Roberts.They were made in 243 Winchester,because of the popularity of that cartridge which made the 257 Roberts pretty much overlooked.
Check the manufactured date link on the Remington Society of America for details.
Actually your Winchester model 70 bolt action rifle was made in the year 1937,which makes it a pre-war model 70.This was the first year Winchester ramped up production and made 9334 model 70 rifles.A pre-war model 70 rifle in .257 Roberts will bring between 775-1,850 dollars for a rifle showing between 60%-90% of it,s original finish,and a receiver that has not been drilled and tapped for a scope mount.If by chance that you have a super grade model 70 you can add 100% to the above listed values.All pre-war model 70 rifles should have only 2 holes drilled in the front of the receiver(none in the back) A extra set of holes will decrease the value by 50%.If your serial number has a Letter D suffix indicating a doubled up serial number;this variation will command a premium because of it,s rarity.
50-500 usd
Based on an exhaustive Google search, I don't believe so. They did make a .257 Roberts, at least in 1942, and it is rare. Sometimes these were reamed out later by gunsmiths to .257 Weatherby Magnum, and the barrel markings may or may not have been changed.
About $650 depending on manufacture date. If it is pre '64 you got a gem worth 3 times that
46% of 257 = 46% * 257 = 0.46 * 257 = 118.22
17 Remington, 220 Swift, 222 Remington, 223 Remington (5.56mm), 22-250 Remington, 243 Winchester, 257 Roberts, 308 Winchester (7.62mm), 7mm-08.