From what I understand, having researched this in detail today, is, you don't.....
That is, the rear sight is dovetailed in to the barrel, and the front sight is screwed on .
In order to sight in the rifle, you would need to use a small brass headed hammer and 'tap' the sight in order to adjust the point of aim.
There are options for mounting a peep sigth, such as from Williams Gun Sight, which has the ability to adjust for elevation and windage quite easily.
Alternatively, you could mount a scope.
Apparently, some of the earlier models require having to drill and tap holes in the side of the receiver in order to mount the scope base.
By drifting the front sight
top adjust the elevation up and down, the side adjust the windage right or left. .
Ebay has usually side mounts that fits the Savage 340 , Glenfield side mounts
The savage model 340 series was made between the years 1950-1985.
Savage (Stevens) Model 340
The average savage model 340 is currently valued at between 100-200 dollars depending on the condition of your firearm.
savage arms
Without a serial number,I can only say that the savage model 340 was made from 1950-1985.If you would include the type of sights,barrel,barrel length,and stock design It would better help me in deciding with in which years your savage model 340 was produced.
The Savage model 340 was made from 1950-1985,while the Savage model 340C,and 340S deluxe were made from 1952-1960.Yours could also be made during this time span.
1950
The value of a savage 340 BC 222 rem would actually depend on a couple different things. Some of these things would include the age and condition.
340.The Savage Arms model 340 was made between the years 1950-1985.The model 340C was made from 1952-1960.The model 340V was made in the 1960,s.