1 in 16"
From the Speer #11 Reloading Manual.
Can't be answered without knowing who made it.
The Savage 340 E in .222 Remington typically has a twist rate of 1:14 inches. This twist rate is designed to stabilize lighter bullets, usually in the range of 40 to 50 grains, which are commonly used with this caliber for varmint and target shooting. Always verify specific details with the manufacturer's specifications or a reliable source, as variations may exist.
http://www.gunpartscorp.com/Products/198420D.htm
$250 - $300
The Savage 340 was a basic hunting rifle, solid and accurate, although it may never win any beauty contests. It was chambered for 30-30, 222 Remington, 300 Savage, and 22 Hornet. Since the model 340 has been out of production for many years, parts may be an issue, but the rifle itself is rock solid.
four
depending on condition, from $150 to $275. extra mags, scope mount and a scope may add a bit over the bare rifle price.
If it was manufactured before 1/1/1969, it probably doesn't have one. If manufactured later, it should be clearly marked on the receiver.
The savage model 340 series was made between the years 1950-1985.
Ebay has usually side mounts that fits the Savage 340 , Glenfield side mounts
Savage (Stevens) Model 340
The average savage model 340 is currently valued at between 100-200 dollars depending on the condition of your firearm.