I was wondering what is the shortest length that you can get away with(12",13") concerning either the 308 case family or the 7x57 family. I was shooting a 308 factory encore but would like to get back to the handiness of my 12" contender.Thanks in advance.

The real question is, what muzzle velocity are you after? With pistol length barrels, you loose ~50 fps/inch. Going from a 15 to a 12 will cost you 150 fps. Personally, I think the those rounds need a 14-15" barrel to effectively burn the amount of powder they hold. If you want a 10-12" tube, then consider something on the BR case, ie 1.5" .308.

In 1978 I had an XP-100 redone to meet IHMSA rules The barrel length is 11" It likes 3031 and 150 gr Noslers you can get plenty of velocity and energy flip side is you get plenty of muzzle flash. I have shot mine down the 100yd tube at Bass Pro there is a ring of fire looks like smoke ring goes down the tube about 5 feet. I still shoot this from time to time and enjoy long range shooting