All 9,3x62s have long throats, like most smokeless cartridges that were designed back in the day when heavy, round-nosed bullets were pretty much the rule, whether for military or sporting rifles. But the CZ magazine is indeed longer than the original standard magazine length: The round was designed to work in the standard K98 Mauser military action, which typical has a 3.30 inch magazine, so it is indeed possible to crowd some more powder in there, especially with spitzer bullets.
One of the reasons I use Big Game with 286s with 9,3x62 is have found it less temperature sensitive than R17--and not just in that application but every other combination I've tried. Since it's s spherical powder, you can also get a lot inside the case, even with very long bullets like the 286-grain Barnes TSX.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.” John Steinbeck
