What is the value of a Remington Model 1912 Pump 22 Rifle shoots shorts long and long rifle bullets?

Anywhere from $100 to $600, depending on EXACT model and condition. Average price is about $200.

That answer is wrong, unless it's a tomato stake (rusted to heck) it's worth more.

A model 12 is worth at least 3-400 in very good to Excellent it's 600+ gun and mint can exceed 1,200 if you have original box.