Gotta agree with RL338 416’s are awesome. Love my 416 Taylor improved and 416 Remington. I have made brass for my 416 Taylor imp out of 338 win mag brass, and 458 win mag. Bullets and proper headstamped brass is hard to come by these days though.416 , my favorite caliber.
Biggest think to think of is factory ammo or rolling your own. Both ammo and reloading components are hard to come by for both.
I am a lefty so it would be easier to get an another .375 Ruger and swap barrels.While the 338 Win Mag is a great cartridge and performs very well on large game, I have to admit that my 416 Taylor is a lot of fun too!
And I am not using full powerhouse loads, as I am currently loading 69 gr of Re-15 with 350 gr TSX bullets for 2415 fps and 4532 ft.lbs of energy, and producing .4" groups at 100 yards w/ an SD of 9. Sighted in for 1.3" high at 100 yards provides a 150 yard zero, and 3.1" low at 200 yards where velocity has dropped to 1942 fps and 2930 ft.lbs of energy. This should still provide enough velocity for reliable expansion for this bullet. Recoil in my lh Ruger Mk II in a laminated stock and 22" King barrel is very manageable...and there is room for improvement as you are supposed to be able to get 2400 fps with 400 gr bullets.
I also have some 350 gr Speer Mag Tips to try in it, and would love to find some 350 gr A Frames to try as well.
The nice part, is that it only takes a barrel change to make that 338 into a 416 Taylor, and you can neck that 338 WM brass up to make 416 Taylor. And if you prefer properly headstamped brass (as I do), you can get it from Quality Cartridge! (and I did!)
For comparison, Federal's 225 gr AccuBond ammunition gives 2800 fps and 3917 ft.lbs of energy at the muzzle. Sighted in 1.8" high at 100 yards, with a 200 yard zero (2475 fps and 3059 ft.lbs), is 7.4" low at 300 yards with 2320 fps and 2689 ft.lbs of energy. Recoil is still manageable, but much more pleasant with a LimbSaver recoil pad! (Nosler shows 75 gr of Re-19 for 2784 fps with the 225 gr AB)
While remaining energy at 200 yards is very close on paper, the 416's larger frontal area is going to make a a larger impression on the game it hits (pun intended!)
Honestly...I would keep the 338 Win Mag and acquire another rifle to build the 416 Taylor, or get a Ruger Guide Rifle in 416 Ruger, if that's your final choice. (Unless of course, you are a lefty like me! then finding a LH 416 Ruger may be a challenge!)
While it might not be apples to apples the 500gr A-tip load in my 416 Wby has very impressive numbers at distance. Granted I never shot it beyond 600yds , but this combo shows big bores can go the distance.A 250 Berger might have better long range ballistics in the 338 but the point is not always are the big calibers at a disadvantage.
Too bad you are on the other side of the border...and it is a bit of a pain to export rifles...but it can be done for about $350 CDN last I checked; the rules and costs have changed some - my last import from the US was less money than previous imports...save you the trouble of finding another LH 375 and having to get it done...I am a lefty so it would be easier to get an another .375 Ruger and swap barrels.