hey there,
i have been swapping barrels out on my savages for the last couple years, its pretty easy and straight forward... i am not sure if it would be something you would want to do in the field, but i am sure its doable...
what you need:
-savage barrel nut wrench
-vice
-some sort of hardwood block, similar material with a hole drilled in it with a diameter similar to the barrel diameter and cut in half to clamp the barrel in the vice to prevent marking it
-go and no-go guages (i actually use fired cases - regular fired case = go guage and fired case with a peice of tape 0.002" thick on the headstamp = no-go guage... they may not be perfect but they work...)
-torque wrench and appropriate driver bits for the action screws, scope mounts and scope rail
procedure:
remove scope, remove the scope rail if it protrudes over the barrel nut, drop the barreled action out of the stock.
place the barrel nut wrench on the barrel nut, then put the barrel in your blocks and clamp them down in the vice to hold the barrel with enough force to stop it from spinning.
turn the barrel nut counter-clockwise (when looking from the muzzle end) to loosen.... you may need to use a couple blows with a hammer to the wrench or a cheater bar when loosening the barrel nut for the first time from the factory...
once loose i spin the action off the barrel, and remove the barrel nut from the barrel
place the new barrel in the blocks and tighten the vice, spin the barrel nut onto the new barrel as far onto the threads as possible, place the wrench on the nut
now place the go-gauge (fired case) in the chamber of the new barrel, with the bolt closed in the action.
spin the action onto the new barrel until you feel the bolt face of the action engage the head of the fired case and you feel resistance as turn the action onto the barrel.
spin the barrel nut down onto the action finger tight and test to see how easily your bolt moves as you cycle the action with the go-gauge in the chamber
there should be a slight "crush" feeling, meaning the bolt should move with a little bit of resistance when you open/close the bolt.
if your bolt just falls shut with no resistance its too loose -tighten the action on the barrel a little more
if you feel you have to strong arm the bolt to open and close it on the go-gauge you have it too tight - loosen the action on the barrel
when you think you are at the right headspacing tighten the barrel nut down on the action with the barrel wrench (i tighten it as tight as i can get with one hand on the wrench pulling towards me with out bracing my self against anything... not Savage tight... word is Savage arms employs a 500lb Gorilla on steroids to tighten the barrel nuts in the factory)
test to make sure you still have that slight "crush" feeling on the go-gauge... if you don't you may need to loosen the nut and fiddle with it untill it feels right when the nut is tightened down...
then put the No-go gauge in the action and try to close it... if it won't close you are golden... if it does close you need to fiddle with it a bit more untill it closes on the go-gauge and not on the no-go gauge....
now put the action back in the stock, torque the action screws back down (i torque mine to 35 inchlbs) and re-mount the scope....
fire a group at a target and take note of how far out of zero your new barrel/round is shooting from your old barrel and write that down so when you change the barrel back you know how much to adjust your scope back to...
now zero your scope and you should be good to go
once you get good at it you should be able to swap a barrel out in about 10 minutes
this will work for switching between any rounds that use the same size bolt face... eg: 308 win, 243, 22-250... etc... if you wanna go from 308 to say a 223 you will need to do a boltface swap as well before you set the headspace...
sorry this was a little long winded... if you have anymore questions let me know...
savageshooters.com has lots of info on their forum about barrel swaps/boltface swaps too...
orch