I see that what the .300BO does promise is exciting. What's missing are the actual products and real world numbers, in performance and retail.
So far, what we have is largely internet vaporware, SHOT show announcements, and a lot of talk about what might happen.
No, not really. I have sitting next to me a 300BLK barrel and about 300rds of Gunn Ammo 300BLK supersonic rounds. This weekend or next the barrel will be turned into a complete upper and I'll be in business.
Right now, you can buy factory 300BLK complete uppers from Noveske, CMMG, and AAC, and complete rifles from the first two. Companies that have announced complete rifles, some already in journalist hands, include DPMS, Bushmaster, and LMT.
300BLK ammo is readily available at most major online sellers, with loads from Remington, CMMG, Gunn Ammo, and Hornady (300 Whisper loads stated to be compatible with 300 Blackout). You can also use almost any 300 Whisper load, although not many companies have been or are loading to that specification.
No need to wait for magazines, bolts, or any other special parts for 300BLK in an AR.
From where I stand, as someone who's been looking at 6.8 SPC for several years and 300 Blackout for the last twelve months, is that there is little to no practical difference in current availability of barrels, uppers, and ammo, little difference in price and what there is favors 300BLK, and only a modest difference in availability of complete rifles (for those who can't push two pins together). This is not vaporware. Sure, it's not yet available at Walmart, but in the major hunting state I live in I have never, ever seen 6.8 SPC in a gun store - never 6.8 SPC ammo, never complete rifles or uppers. To me 6.8 SPC is also a purely special-order and online-order item, and 300BLK is already there, with promise of being a normal retail item in the very near future.