LG,
I should add that I don't know much about what's called "Tactical Shooting." I have some friends that do gunsmithing for tactical shooters -- their offhand comments are that it pays a lot better than gunsmithing for benchrest shooters. There's a fair bit to be gleaned from that, but it's just gleaning.
One of these guys does a lot of work for the military -- not military shooters, but "the military" if you see the difference. Aside from matters of ammunition resupply, as I remember he believes most of the tactical needs would be better met by an appropriate .30 caliber, reserving the .338 for certain, specific tasks. For various reasons, that's not going to happen anytime soon.
My opinion only -- "tactical shooting" as an element of combat is very different than the new competitive sport of "tactical shooting," just like "varmint hunting" is different than competitive sport "benchrest." Military & police needs are also different, both from each other and the sport.
Long preamble, but needed that to say I know next to nothing about tactical shooting as a competitive sport. Which means I also don't know the overlap between it and long-range benchrest. I probably should have just kept my mouth shut -- too many guesses about what you're trying to do, and I'm sure to get a significant part of it wrong.
For example, in both 600 and 1,000 yard benchrest, the small 6mms now dominate. Just go look at the match results
http://internationalbenchrest.com/results/long_range/_longrangeindex.php
You can't trust the equipment reports too far, but there is so much data there it should present a pretty clear picture about chamberings and bullets.
So, what is it about Tactical Shooting that makes, say, a 6BR not the best choice? I haven't a clue.
Those of us sticking to the bigger calibers in 1K benchrest are mainly old-timers who began long-range shooting in the last millennium. Or, a few of us who see the ballistic advantage of the heaviest of the .338s, and are willing to make the many compromises involved to see if we can get them to outperform the proven winners.
That performance quest always goes back to what you see in "Match Results," and I'm afraid that's probably different than what you're looking for.