I have a 300 Norma (clone), built on a Weatherby mark v action that ive been using for long range deer hunting for many years.
The gun was built by the late Howard Wolfe, an early long range gunsmith from PA, and also an early 1000 yd Williamsport shooter.
He was also deeply involved in creating the 30x378 cartridge in the 60s by necking down the 378 Weatherby case to 30 cal.
He also developed a large custom action at that time having 3 lugs for that purpose.
Best performance for the 30x378 at that time, was with long barrels of 34 to 36". Unfortunatly, there were far fewer barrel makers then, and even fewer who produced long barrels.
For Williamsport shooting, he shortened the long 378 case so that the more available 30" barrels could be used. It produced very good accuracy, and became fairly popular localy, for both 1000 yd shooting and long range deer hunting.
He ultimately started using Weatherby actions also, and built my gun for a Williamsport shooter who unfortunately died after using it just a few times.
I bought it and discarded the lead added heavy bench stock, sent the barrel back to Hart barrels for a weight loss treatment, added a Vias brake, and had Howards son Bob install a pretty new left/right thumbhole stock on it fashioned after a Mcmillan.
Its the most accurate rifle I ever owned, and has long since become the favorite rifle of everybody in the camp, and there are lots to choose from.
Fast forward about 20 years and a visitor showed up at camp for bear season. He had just had a new rifle built on a 700 action and showed me a cartridge.
I said that looks pretty much exactly like my little Wolfey. He had a few emptys also, so we commenced comparing them and checking capacity with water.
There was only 1 grain difference in capacity between the cases we compared.
So as it turned out, old Howard had created the 300 Norma maybe 25 years before it was created.
Frankly, I wouldn't personaly be building one on a 700 action, although I know the designer intended it to be used on those and I for sure wouldn't be using a Savage either.
My hunting load is 97 gr of Retumbo with a 190 SMK, and I know, I know, I'm using the wrong bullets.
Velocity is in the area of 3350, and its like a lazer out to about 1200 yds.
Beyond that distance we just go right to the 300 gr 338 built on #29 of Howards big 3 lug actions.
I personaly see no point or any advantage in necking that case down to 7mm.
With the 30 cal you also have a much better selection of good bullets to use.
There were also guys who necked down the full legnth 378 case to 7mm back in the 70s, and that didn't work out well either.
If I live long enough to need a new barrel, I would go with the 300 Norma over what I have because of the brass situation. Mine has to be made from 378 brass and that's a big pita.
But as for the action, id be afraid of eventual lug set back on anything less than a lapped Weatherby mark v.