Originally Posted by
Daekar
So... I get that the cartridge has enough volume to push meaningful power. I mean, it's not anything groundbreaking, and doesn't illustrate any principles of cartridge design which weren't known already. We already knew that long bullets can work out of small cases and that good velocity can be gotten out of short barrels with the right powder. We already knew that bullets with good drag coefficients maintained energy well. If you want a cartridge that shoots 210gr bullets at 2500fps there are plenty of options and this seems a fine example of that.
The thing that puzzles me is that they're playing this up as a revolutionary improvement in subsonic performance. It's just not, especially if you need a 1:3 twist barrel to achieve it. There is no way you're going to be pushing bullets out of that rapid twist at 2450fps without problems... it comes out to be... what, 588,000rpm? That is just BONKERS fast. Which means you need a whole other barrel for supers or you're shooting some exotic bullet which doesn't instantly self-destruct at that rate of revolution the moment it leaves the muzzle.
If you're shooting these things subsonic, all that case capacity (or pressure headroom, whatever) doesn't matter a hill of beans. If you can't use the same barrel for subs that you do supers, then you are far better off using a whole different cartridge which will be cheaper and more performant in subsonic applications in the real world. Joe Public is not a member of Seal Team Six who can estimate wind drift and bullet drop by dipping their finger in the blood of their vanquished foes and feeling the movement of the air... nothing subsonic is a good long-range cartridge, there are just varying degrees of awfulness. That being the case you're better off with something that doesn't have a bat-**** crazy twist rate and can take even heavier bullets with a larger diameter: a 458 SOCOM, 450 Bushmaster, 50 Beowulf, etc.
As far as the comparison to 45ACP, obviously it only applies to the subsonic performance. It's interesting to consider, though, that 45ACP is basically identical to 300BO at realistic engagement ranges. If I were to build a rifle specifically for suppressed use, I would actually prefer the 45ACP to the 300BO. They're going to carry the same amount of energy but the 45 is going to be a lot more effective at imparting it without exotic and expensive bullet contruction.