This thread’s gotten a bit sidetracked, but here’s my two cents for the OP:350-400 yards with good energy to put down a moose
If that’s all you’re looking to do and you already have a .375 H&H, I’d just work up a snappy 225–250 grain load and pair it with a scope you can dial. Something in the 10–12x top-end magnification range should serve you well.
I have no issues shooting my .375 H&H out to 300 yards, provided I have time to range and dial. If I’m pressed for time, I’ll just hold over. I’ve never hunted moose myself, but from what I’ve gathered online, they’re not exactly made of stone. Plenty of folks seem to take them cleanly with the old 6.5 Swede. That said, I’d personally want a bit more horsepower.
Long-range big bores are a rabbit hole—lots of cartridges .375 and up designed for shooting well past 1,000 yards. Personally, 500 yards is my limit on big game. Too many variables: time of flight, animal movement, wind, etc.
That said, 400 yards is absolutely doable if you’ve got the skill, favorable conditions, and a solid rest.
The .338 Win Mag is an excellent choice, along with several of the Weatherby options mentioned. But a lot of the newer long-range hunting rifles are, in my opinion, starting to look like heavy, tacticool target guns—clunky and less practical for actual hunting.
Bottom line:
- If you want a new rifle, go .338 WM or a Weatherby.
- If you want to use what you have, work up a solid 250-grain load for your .375 H&H, get a good rangefinder and a dial-capable scope, and go kill Bullwinkle.
If I ever get a chance to go moose hunting, I’ll be taking either my .375 H&H or my .300 Win Mag.