If it is installed snug it won't come loose. If you are trying to get a factory installed nut, be prepared for a bit of a battle. The gorrilla at the Savage and Stevens factory takes pride in his work. After you break it loose it doesn't need to be installed very tight. Hand tight works for me. I've never had one come loose.
Be warned barrel swapping can and will become addicting. I have two Savage actions, both long action. One is for my magnum barrels and one for my standard size barrels(I don't shoot 223 sized). My collection of barrels include 22-250, 220 Swift, 308, 30-06, 300win, 7RM, 284win, 300wsm, and a 338 barrel that I looking for a reamer. Probably make that one a 338fed or 338wsm.
It only takes about 5 minutes to swap a Savage barrel. Here's the basics.
Put action in action wrench.
Put nut wrench on nut.
Break loose barrel nut.
Screw off barrel.
Screw on new barrel.
Put go-gauge or fired/sized brass in action.
Check with no-go-gauge or brass with tape.
If its good, your done.
If not, re-adjust barrel until done.
That's it. I could have done two barrel swaps in the time it took me to type this.
If you only want one Savage action, you can also swap bolt heads. It takes less time than swapping barrels.
Here's the lowdown on swapping bolt heads.
Remove bolt from action.
Remove Bolt Assembly Screw(installed by same gorrilla at factory).
Remove firing pin.
Remove bolt head retaining pin.
Remove bolt head.
Re-assemble in reverse order.
Check firing pin protrusion.
Get the BAS on tight. I have had one of these come loose.
Both can be done in about 5 minutes.
Be careful. Check your work often. Watch for signs of addiction.
Realizing you have a problem is the first step...I'm not addicted. I can stop anytime...Anybody have a 338 reamer?