Older then when they started making them, for a firearm to be antique it has to be pre-1899. There's also a curio and relic classification but a 870 will not make it into that list.
50
2012 remington express max
30p
what is my 12 gauge pump Remington trademark stamped 1903 may 5 to may 5 1905 serial number u 60212
Depends on model and age.
Remington 700's are center fire rifles. Remington does make a very good 12 guage shot gun called the 870 (pump) and the 1100 (auto)- those are the popular ones i have both
100-1000 or more depending on specifics
the Remington .32 model 141 is not a shotgun but a pump action dear hunting RIFLE. It was made between 1938 and 1950, and has a value in good condition between 250 and 300$
You can download an owner's manual for free at Remington's web site.
depending on the condition 100.00 to 250.00.
your Remington is going for 130 dollars in fair shape to 295 dollars for one in very good condition.
1930-1933 (barrel is code stamped w/ date) Remington Society of America: http://remingtonsociety.com/rsa/questions/barrelcodes