The reason why some barrel nuts are so tight:
1.The recoil lug is not perfectly flat, there are high and low spots and some amount of "cup". This acts like a split lock washer. Just check the witness marks on a take-off lug.

2. The barrel nut usually has some burrs on the mating side from the serration cuts. This acts like a star lock washer. Just check out the galling on the nut.

3. On blued guns, some will suffer from "salt creep", a condition where not all of the bluing salts are flushed from the tight crevises and thread joints causing that white "gunk" to appear that everyone thinks is a thread lock agent. This stuff is caustic, and will make things that are mated close, "bite".
Savage uses a short barrel nut wrench with a tube for a handle. The torque wrench is inserted into the handle to make for a total length of about 18". The nuts are routinely torqued at 75 ft/lbs. These wrenches are the "clicker" type, so it is possible to get them tighter than 75 ft/lbs if one was in a hurry.
Now just because it is torqued to 75 ft/lbs, doesn't mean it will break loose at that,see the above.
Torquing a barrel nut and torquing a shouldered barrel are 2 different things. The added nut will make the joint tighter.