It could be possable that your Winchester model 670 does not have a serial number.The gun control act of 1968 mandated that serial numbers be present on all firearms made.The Winchester model 670 was made from 1967-1973.If it was made after 1968 then it would be located on the receiver just behind the barrel.
a serial number is needed to give you an exact age of your rifle.I can say that your winchester in .243 cal.was made between 1956-1973.
No such model number
Only one rifle was made as a lever action in .243Win caliber,and that was the model 88 rifle.With the serial number that you have provided,your winchester model 88 was made in the year 1961.
1976
Winchester introduced the .243 Winchester cartridge in 1955 for the bolt-action Model 70, and the lever action Model 88. As far as the year of manufacture of a particular rifle, you will need to provide the manufacturer, model number and serial number to trace it, but if chambered for .243, it logically cannot be early than 1955.
1967
Don't know about the 243 carbine but the serial numbers for the model 100 go up to 263170 on the site I use to check dates. That number sounds about right but the model 100 was made in a .308 and a .243 with the .308 being the majority.
50-300 usd
Lets start out with the fact that the Winchester model 100 semi-auto rifle was chambered in 243 Winchester,284 Winchester,and 308 Winchester only!Your serial number indicates that your rifle was made in the year 1965.These rifles range in price from 250-400 dollars,depending on overall condition and a good bore.
Between 300-500 dollars,depending on overall condition of the rifle.
The 243 Winchester caliber was introduced in the model 70 bolt action and the model 88 lever action rifles in the year 1955 by Winchester.
The twist rate in a Winchester 670, 243 caliber is 1:10.