Adjustable gas block is essential if trying to run a short barrel or subsonic loads (I’ve used one on a 7” 300 BLK)
Opposite end of the spectrum from a 300BLK :D, you could never get a 223 with 40's to even function in the realm of subsonic with an AGB or magic pixie dust...............doubt the OP has a 7" barrel either.......guess we will find out
