I know this is an older thread, but I wanted to add that I was told by a very talented gun maker and shooter that I needed a bolt larger than a .700" to handle Lapua bolt face cartridges (Including the Norma Mags because that's what I was trying to build. At the time, all of the aftermarket actions offered .750" bolts, and that's what he stated was necessary. However, now, there are some who split the difference and go with a .725" bolt diameter. Not sure what the Savage .338 Lapua Long Range was wearing, but I never heard of but 1 sized bolt for them. Correct me if that one was larger. I've also been told that I must have a large shank to run an UM or Short Mag of any sort. While not larger than the belt diameter on a belted magnum of old, the .404 Jeffrey-based cartridges operate at 3,000 - 5,000 more PSI max avg pressure compared to many of the belted magnums. Maybe Roy Weatherby was correct making his massive 9-lug bolt.
All I will say is that if I ever decide to build my Norma Mag wildcat, I will be using an aftermarket action, not a Savage. The cycling of the action is not generally really smooth. There are some things that could be done to polish it up, perhaps. I am the occasional shooter/hunter, and therefore, probably couldn't shoot an expensive aftermarket any better at 3/4 mile than I could a Savage. I am that giy with minimal skill who enjoys the heck out of screwing on a pre-fit barrel and shooting bugholes @100yds, since most shots here on game occur at around that distance. I think the worst I've done has been with a Shilen Select Match .308 Match pre-fit that would group no better than around 5/8 - 11/16" @100yds. The best I've done is a couple that would shoot tiny clusters with holes all connecting around 0.188" @100yds with a Varmint weight Criterion in 6.5x47 Lapua, and a Preferred Barrel Blanks wildcat .270 caliber based on a necked up Creedmoor with special throating. I had a black olastic Axis in .270 Win that shot 1/2" right from the factory with a little support under the barrel channel. Then I've had a new Axis 6mm ARC shoot maybe 1 1/2" @100yds, and a .300 Win Mag in the Model 111 Long Range Hunter that wouldn't hold 2 1/2 - 3" @100yds. It is fun to tinker, though.
I will agree that the Savages are not nearly as big a draw now as they were even 10 - 20 years ago. The quality has seemed to decline of some of the parts, and the top bolt release has given way to the new Tupperware 110 dipped in various color schemes and outfitted with spiraled or carbon wrapped barrels. The lapping process is atrocious. (What lapping process?!?!) I am currently moving from Boyd's stocks to chassis systems and then on to aftermarket actions like ARC and Kelbly because they are designed to run Remington stocks, triggers, and bottom metals. The disadvantage is cost. With more money to play with, I can build nicer toys. With little funding, I can still by a functional and accurate hunting rifle, bit may not be able to customize it as much as I'd like. As more makers of parts shift to supply M5 bottom metals, actuons with contiguous recoil lugs and rails that have a shorter throw/faster lock time and the all-important butter-smooth action with carbon barrels and stocks, there are going to be fewer Savage parts made. The only thing that may survive is the action thread pattern because some aftermarket companies have adopted it- namely Zermatt and ARC. What it has going for it is that the price of the aftermarket actions and component builds is a barrier to many working folk that could buy 2 Mossbergs (or more) for the cost of just an action. With the price of the Savages steadily increasing, however; there are a few (at least) options less expensive than the high end Savages that are MUCH better rifles.