My shooting Buddy is a big 300BLK fan, makes his own brass and all the rest. I just don't see the attraction.
I tried a 30 cal that's a lot more conventional, the 7.62x39; starting with a Century Arms Mauser sporter that was rebarreled for it. It was a disappointment, mainly because the rifle was just not up to a working par, and the surplus ammo I was feeding it was just this side of being pure junk. I sold it at a gun show and was glad just to get anything for it.
Then the earlier version of the Savage Scout 10FCM came out in 308 and 7.62x39, and I sprung for one of the latter, thinking vaguely that the bolt face might lend itself to some variety of PPC cartridge. It was a completely different animal from the Mauser.
The bore is configured for both .311/.312 and .308 bullets; with a forcing cone and a genuine 30 caliber bore. The rifle is a solidly, tightly built Savage with a carbine style barrel contour and length, and a workable synthetic stock. There's also the Accu-Trigger and a D/M.
I removed the rear sight and Scout style scope mount, and replaced it with a conventional 20MOA base. IMHO the Scout favors clip slot feeding. The Savage 10FCM has no clip slot, feeds from the D/M, and has no need for an LER mounted scope. I bought some American made ammo, and the rifle stands up to the goal of being a brush gun for deer, etc. Were I to handload it for such an application, it would be a prime contender for .30-30-specific bullets.
Then I started handloading. Right away, a load using the HDY 110gr V-Max and a nearly max load of IMR-4198 went right to the top of the charts. It's very accurate. I also tried the HDY 110gr GMX, a plastic tipped copper monolith, intending that the greater length would translate into somewhat of a stretched downrange trajectory. But so far, I haven't gotten it to shoot anywhere near as small as the V-Max. It's still early in this game, so I'll try a little bit of development. Eventually. Maybe.
The point of this longish story is that the BO can be a fun niche cartridge. But I also think the 7.62x39 loaded with .308 bullets in a .308 barrel can do much the same, and do so with nearly none of the special tasks associated with some BO applications. Bulk it up with some heavy projectiles, treat the load like a pistol cartridge, run a silencer, and it will probably haul that mail pretty well, too.
Greg