You're probably thinking about the 300 Blackout. Essentially a cutback 308 case. Seem to be popular in the very short barrel platforms, nothing special for long range use but OK for up close and personal.
That's a purty looking barrel... What twist rate did you get?
I built a 308 two years ago. They are a blast but I had soooo many issues with cycling. I had an adjustable block on but took it off due to being a single shot semi auto, don’t get that confused with full semi auto like the news did haha. I bought the adjustable buffer long story short after dissembling and reassembling more times than I can count I ripped that off and put on a regular one. Still didn’t fix the issue. I tried everything including a different lower still had issues, it would not cycle. Everything was torqued properly and everything was installed correctly which had me so baffled. It wasn’t the ammo that ran fine in my buddies rifle.. come to find out after taking the barrel off I measured the gas port and it was to small. Drilled that thing out and now she runs like a champ. I’m actually going to rip her apart again to put that adjustable gas block back on to tone her down a bit as she launches the casings lol.
Haha it's a eBay special, I built this during COVID when you couldn't get anything.
