There is no Remington Model 6 pistol, there has been however cases however of Remington Model 6 rifles converted to pistols by gun or "home" smiths. NOT Remington. As such the value is whatever someone will pay, but generally not much.
6 mm
According to Remington's website, that model was made 1928-1933.
In Real Good shape , the 270 Long Action Model 7400 is worth $250 too $350 less the scope .
your Remington model 6 was made in 1998,due to the S prefix on the serial#.
300-500 dollars depending on overall condition and the caliber that the rifle is chambered in. I'll just add to be worth 500 it would have to be in screaming mint condition you have to remember the model was created to be an inexpensive competitor against the other boys rifles of the period.
It is unusual vs. rare
http://remingtonsociety.com/rsa/service
1919
CHeck the receiver and barrel
1928, will be date code stamped. check link on Remington Society.
The Remington 700 is a model number. It is chambered in different calibers. The 30-6 being one of them.