Just to continue the discussion, because I'm enjoying it, here's the thought process that's leading me down the 9.3 road (other than the fact that I've been loading and shooting the 9.3x62 for a while). I think it's still relevant to the discussion here because of the .375 bullet data included in my tabulations.
Two attached tables show the common hunting bullets in .358, .366, and .375 caliber. I focused on those for two reasons: 1) some states like Iowa with a .35 caliber rifle restriction I'd like to take advantage of (sorry .348 Win in the safe), and 2) by a rule they're shorter overall than the .30 or .33 caliber 200+ gr bullets, so they'll fit with a longer case in the medium action I'm building on (which unfortunately means they have less overall B.C., but that's what 7mms are for). Note that there are a lot of other options I didn't tabulate because they had relatively low BCs for weight and are bullet constructions that I'm just not really interested in hunting with.
The first attachment is a table of these bullets sorted by G1 BC. As you can see, the .366 250gr Accubond comes out on top. The only ones that best it are the high-300+ gr match bullets for .375 (.375 390gr A-tip, 379gr/407gr/410gr Berger), which I did not include in the table because personally that's not something I would hunt with at the velocities you can drive them in a lighter rifle while still maintaining manageable recoil. That's obviously subject to personal preference and interpretation and hand-waving. My takeaway from list #1 is that the .366 250gr Accubond slightly edges out everything else for BC in the hunting bullets I'd want to use. In .375, the best viable lead option on this list (purely focused on BC) looks like the 300gr Accubond. I have no experience with copper bullets, but obviously the 260gr .375 Expansion Tip is pretty far up the list also if that's your thing.
The story changes a little when you sort by G1 Form Factor (second list). This sorting is a good way to capture the relative bullet weights and what muzzle velocities they can be driven to by the same cartridge, which I believe is particularly relevant to these "medium bore" hunting cartridges, where your maximum reliable hunting range is going to be strongly driven by the range of minimum expansion velocity that can be obtained with a relatively "heavy" bullet in a cartridge of manageable recoil. In this list, the .366 250gr AB is still essentially at the top of the list, bested only by the copper 260gr .375. However, the .375 ordering changes significantly when you sort by G1 FF. In this case, the 260gr AB, 250gr TTSX, and 270gr LRX all best the 300gr Accubond that has a higher BC. The 225gr .358 bullets also jump up in the list significantly relative to what their G1 BC numbers would have you believe.
Now, onto more of my decision process. My favorite sort in this is bullet type followed by G1 FF (3rd attachment). In that sorting, the .366 comes out best or second best for the bullet construction I'm interested in loading. It has the best Accubond, the second best A-frame (behind the 270gr .375 A-frame, which has a notably lower G1 BC), and is second best to the 225gr and 250gr .358 for Partition bullets (and again, the .358s have a noticeably lower G1 BC). Interesting to note, for anyone that would ever consider shooting solids at range, the .366 also has the best Nosler Solid by both G1 BC and G1 FF. So, add all that cherry-picked data up, along with some handwaving and sprinkle a bit of "I just need an excuse to do this" on top, and I'm going to chase the 9.3mm bug for a "longer-range" "medium-bore" hunting cartridge.
I'm pretty much settled on a 33 Nosler necked up to .366. Preferred Barrel Blanks thinks they can accomplish this with reamers they have in stock, and I'm working with Redding to see what the best route is for dies. The cartridge seems to be quite similar to a .30-06 in case volume vs bore area and bullet weight, and GRT data indicates it responds well to a lot of the same powders the -06 and regular belted mag cartridge families like. Several powders show promise of besting 2800fps muzzle velocity out of a 22" barrel, and COAL with the 250gr AB will still fit inside a 3.25" Medium Length magazine, which is what I'm after. Those muzzle velocities will push that 250gr AB out beyond 700yds at the altitudes I shoot while still maintaining effective expansion velocity of 2000fps or greater (final attachment). Note that 36 Nosler, 9.3-300PRC and 9.3-375 Ruger all give higher performance, but none of them are going to be a good fit in a 3.25" magazine. The 33 Nosler case is a bit shorter, but still has good brass available, so that's what I'm leaning towards.
And yes, I know, a 300WSM with heavy bullets offers all-around better ballistics out of a medium action than anything discussed here, but what's the fun in that?
