Well I'm not an appraiser and it is difficult to value something when not actually being held but in your close photo the rifle does appear to be in pretty nice shape. The metal pieces would have been "blued" and the color looks like it has started to turn to somewhat of a plum color. The stock looks to have taken on a nice patina over the years.
If you could:
-Get a closeup photo of the lettering on the barrel. You want to make sure the lettering is "crisp". If it appears to be rounded over, it could indicate a possible re-blue which would detract from the value.
-Get a closeup of the butt plate. That is the portion that would be placed against ones shoulder when firing. That plate should be essentially even with the wooden stock. Should the plate be proud of the wood, that would indicate the stock having been sanded and refinished which would detract from the value.
-Look over the stock for any cracks or splits. Remember, these guns were used primarily by kids and did not always receive the best handling. Obviously, the fewer splits or cracks would only enhance the value. While on subject of the stock. Look at the finish, it should simply be an oil finish on a walnut stock. If it looks shiny then it most likely was refinished at some point with a finish such as polyurethane. Sometimes you will see this finish "spill" over onto the metal parts when done in a particularly poor fashion.
-Examine the metal surface and the finish. When original but used the rifle should exhibit an overall similar look to the finish with additional wear at certain areas. Wear areas would be where the bolt gets cycled and where one places their hand of the their support arm when firing. Sometimes you will see additional wear at the muzzle end of the rifle. This happens when a careless shooter is laying on the ground shooting and allows the end of the barrel (muzzle) to dip into the ground.
Guns of this sort are not in the best market for sellers right now. Value, as with anything, is dependent on originality and condition thereof. You could have a $250 rifle or a $1,500 rifle. My guess is that your rifle would be somewhere in the middle of those two values (retail value) but better photos and a closer examination are necessary to pin it down.