Im running these in a 16" and honestly I dont really need the extra 1/2 gr but im in the go big or go home mindset and Ive used a heavier charge with the 77smk which are slightly longer so I feel safe with the load but I know pushing past max 223 loads things can escalete quickly. I want to duplicate the tap 5.56 load rather than the weak .223 tap which from what ive seen is down 150~fps from the 5.56