quad
Another Hooligan
You can buy an AR in 5.56 and put a 204 upper on it, or build a 204 from parts. As for a 243, thats an ar10 platform, and the upper wont mate to an ar15 lower. I know remington makes a 243 in the ar10. It was nice, but heavy compared to an ar15.
http://www.remington.com/product-families/firearms/centerfire-families/autoloading-model-r-25.aspx
As for the 300 blackout....I'd much rather have a 6.8.
http://www.remington.com/product-families/firearms/centerfire-families/autoloading-model-r-25.aspx
As for the 300 blackout....I'd much rather have a 6.8.