[Gdirty5]

http://shop.shopnoveske.com/collections/rifles/products/noveske-cqb-rifle

I think pretty much anyone who makes a 300blk rifle (just about everyone now a days) can sell a factory SBR. DD sells it in pistol configuration for their MK18 or as a SBR.

 

[SpringerTGO]

I bought an LMT Defender 2000 in 5.56 a while back. Then I did the paperwork, and when it was approved I put a 10" 300BLK barrel on it. It only takes a few seconds to switch between the 2 calibers. It's not the cheapest way to go, but it is very versatile.

 

[ronin.45]

I've looked at the LMT, LWRC, and DD in addition to the AAC. I still think the AAC is the best bang for the buck. I just wish AAC would make some.