Just found a place where they had .300BLK allegedly in stock. 150gr, wait-list for the 220gr I wanted.
https://www.gorillaammo.com/
I asked at one of the local gunshops and they said they shoot it (former Marine) so I ordered a bucket - 175 rounds for $250 including shipping. Not great, but better than the $50.00 for a box of 20 of Rem green/white box I saw at the same gunshop.
I've heard of Gorilla Ammo but know even less about them than I do Detroit Ammo, which isn't a lot. Detroit Ammo Co. calls themselves Your Source for Custom Ammunition from American Manufacturers and says they have ammo in stock. They have 12.7x42mm, the generic equivalent of .50 Beowulf, 85gr Lehigh Xtreme Cavitator ammo for .30 Carbine, and some reloading components including the 176gr Lehigh subsonic .308 Controlled Fracturing bullet, among other things. These are both unusual looking bullets, but what do you expect from Lehigh? Some ammo is on sale including .500 S&W Magnum shotshells loaded with 300 grains of #12 shot. I've used .22 LR and .22 WMR with #12 shot but never seen it in such a large caliber. CCI usually loads #9 shot in other calibers but also sells light loads of #4 in some of them. BTW, in case you didn't already know it,
#13 shot is also called
dust, and #12 isn't much bigger.
https://detroitammoco.com/ I got an email from TacPlaceLLC that says save $10 off each case of ammo until the end of the day Friday November 27th. Use code 10OFFTURKEY. I don't think I ever heard of them, but if they have cases of ammo and they're $10 off, it's worth looking into. They say, "If something is sold out, or you don't see what you want. Please come back tomorrow, as we upload new ammo daily. We offer fast and affordable shipping, as well as special deals for signing up for our ammo club email!" All I see right now is Barnaul from Russia in a half-dozen calibers, with polymer-coated steel cases and non-corrosive Berdan primers. 123gr 7.62X39mm FMJ is $210/500, 115 grain 9mm FMJ is $285/500, and 62-Grain .223 Remington JSP is $350/500rds. They have 145gr .300 Blackout FMJ at a price I wouldn't want to pay, and the cheapest ammo is 60 Grain 5.45x39mm.
https://www.shootammo.com/