Answering the questions...
1) Big bore .50+ calibers
To establish "cartridges you are familiar with in this group" credentials, I should say that I own a .470 NE Krieghoff double, a Mauser 66 .458 Lott, a Blaser R8 .458 Lott; I own or have owned 5 different ZKK 602/CZ 550 (.375 H&H, .416 Rigby, .458 Win); and I have shot a meaningful amount of rounds from .500 NE, .505 Gibbs, .500 Jeffery and .460 Wby.
I will spare you the dissertation and get down to the bottom line:
1- There is not a whole lot of difference, at either end, between .500 NE and .470 NE. To me, the .470 is more practical simply due to commercial ammo availability
and diversity, but the .500 NE is, in my mind, probably the most practical .50+ hunting cartridge.
2- While the .500 NE is shootable with reasonable accuracy by almost any reasonably practiced shooter, in a proper weight double (i.e. ~11 lbs.), most if not all other .50+ calibers have too much recoil for most shooters
in the rifles they are typically offered in. Let me explain: somehow most folks understand that a big bore double should weight in the 10 to 11 lbs. range to be reasonably shootable, but most folks insist on bolt actions weighing in the 8 to 9 lbs. range, and many put a scope on them to boot. This has 2 logical consequences:
a) Tell you what: .500 Jeff + 8.5 lbs. bolt rifle + scope = more often than not, shooters afraid of their rifles, and generally wearing a nice third eyebrow (scar from "scope kiss", and boy oh boy can these be painful!)
b) As to shooting accuracy, welcome to the trigger yanking contest....................... and I do not mean spreading a 2" group at 50 yards, I mean missing an entire Buff at 25 yards...................
2) Client hunting-need for a .50+ caliber
I will send you back to
Red Leg's and
Mark A Ouellette's posts.
The one word answer is "no".
The caveat already mentioned above is that in my experience there is not much difference between a .470 NE and a .500 NE double, so, if incurable romanticism is upon you and you MUST hunt your Buff with a double, and you MUST shoot a .50+, then the .500 NE double checks both boxes and is still shootable in classic weight (10 to 11 lbs.).
3) Entry level rifle today like a $10,000 double chambered in 500 NE
The one word answer is "no".
The old adage applies: you get what you pay for, and, if he forgives me
, I will loosely quote
Red Leg a second time, from another thread: "this is the difference between a rifle that will shoot 100 rounds and a rifle that will shoot 100 years."
My own evolution...
I will abstain from giving an advice, but my own evolution has been:
--- like many, I started with the double rifle obsession and the "double square bridge magnum" Mauser obsession (and I can still make a pretty good case for them)... but now I personally take a Blaser R8 to Africa...
--- my first .458 Lott was/is a Mauser 66 weighing 8 1/2 lbs. ... I cannot remember the last time I shot it, but I still remember vividly the headache that 3 rounds produced (a sure sign of a mild concussion)...
--- I HAD to try the .505 Gibbs, .500 Jeff, and even the .460 Wby -
and by that I do not mean just going bang once at a 1/3 square-yard 5 gallon bucket at 15 yards, but grouping 3 rounds in the center of a 6" paper desert plate at 100 yards ... call me a sissy, but I am a lot more consistently accurate with .458 Lott / 500 gr in a 11 lbs. rifle...........
I know, I know, there are plenty of folks out there who will tell us that they split lemons at 100 yards with these canons; God bless them, they are more man than I am
View attachment 526743
3 rounds of .458 Lott / 500 gr TSX full power loads at 100 yards from the sticks with 11lbs Blaser R8 mounted with Selous barrel and Leica Magnus 1-6.3x24 (1" target grid)
--- the two points where my friend
Red Leg and I continue to differ, is that I do not mind walking all day with a 11lbs. bolt rifle, any more than with a 11 lbs. double rifle (we shall see how this changes as I get further and further on the downside of my 65 years); and I still like a "stopper" rifle for Buffalo and Elephant ... just in case ... although I happily concede that I have - so far - never needed one...