I owned a .30-378 TRG-S, and .338rum Sendero Sf and .300rum sendero sf; up until last year. Beautiful rifles, powerful cartridges; but....
I realize they are far from biggest/baddest and were no where near 1mi capable rifles. Yet, I sold them because even though I live in Alaska and could choose to employ any in my front yard, they were not "practical".
Just posting this to mention the other side of the equation and share thoughts on the most underated .338 going, the .338/300win mag.
Not a specialty round. Just neck up .300win mag brass and go shoot it.
Not hard to make; just improve a .338win mag barrel with a hand-held reamer if you're careful.
Not hard to afford; brass is $60 per hundred and you can find it anywhere (if you can find anything).
My experience is that it is the most flexible .338 magnum round going. A .338-06 might even be bettter, but won't yield the performance the .338/300 does.
I've only fired 250gr bullets in mine. But using XMR4350 and 65gr with a250gr hornady or sierra, it is mild recoiling as a 12lb .308win. With 79gr (don't try this at home), it is on par with the .338 rum and .340Wby.
My rifle of choice for this ctg is a Sako TRG42. With a Pac-Nor SS match barrel of Palma contour at 26" it weighs about 14lbs scoped and ready to fire. The barrel is 1:10 twist to allow 300gr bulets. I haven't done more than chamber the barrel. My prior experience was with a modified SS rem 700 BDL and for a 10.5# rifle w/4.5-14x 50mm Leupold LRT it was/is a great hunting rifle for Southcentral Alaska.
My TRG42 is a switchbarrel rifle. Have the orig Sako 42 barrel in .300win, a TRG-S sporter barrel in .300win, .338win, & 340wby, and the .338/300 match barrel. The .300win 42 barrel fits nicely on an opened-up TRG-S stock, albeit a bit long.
Sure, if you're building The 2000 meter rifle, this ain't the cartridge for you.
But if you're tired of losing barrels to burnt throat at 500-700rds, want more than 50 loads per pound of powder, and wonder why you're paying $4 ea for brass; the .338/300 was my solution.
About the only thing I'm debating now is whether to order a .338/300 AI reamer, and If I want another Sako bolt body and a .338-06 AI in a light varmint contour.
Not much beats the M995 Sako action for anything up to the Lapua Magnum. Would really think the .338 Norma would be the best longrange magnum solution in .338 diameter; but that's me. With a Leupold Mk4 10x m3, I feel very well set for 1200yd shooting, but I am just wanting to take Moose with it anyway, and Minute of Rib Cage on a 1400lb bull moose is a **** large minute.