i don't know of any. i know Rob in Exeter has a few boxes, but charges a high price, especially for subsonic. the ammo i have was bought from PSA with free shipping. i've been looking for 300BLK in local stores and keep asking about it, but no one stocks it as i know of. you could always roll your own, thats what a lot of peeps do (but not me). i need to shoot my 300BLK upper more.....