Not sure about 14.5", but my 18" Stealth shoots bugholes with 73gr Gold Medal Berger. Results are less impressive but still usually sub-MOA (and less expensive) with 69 and 77gr Gold Medal Match. The Magtech 5.56/77 SMK Mk262 clone that comes in 50 round boxes is less consistent but still puts up pretty respectable results (mostly tiny groups with occasional flyers). I need to try more Black Hills, as I haven't in years, but once upon a time their remanufactured 69 SMK load was the best for this gun (since surpassed by recent lots of Federal Gold Medal). Hornady Black 5.56 62gr and .223 75gr are both shooting pretty well for me too. It's a good time for high quality ammo right now.
Handload wise, I used to load up 69gr SMKs in LC brass with CCI 400 or BR4 primers and a charge of Varget that I forget (and would probably be different now anyway with their lot-to-lot variation), and that load was always sub-MOA over long shot strings in my Stealth. Now good ammo is cheap enough that handloading for .223 is a waste of time for me; I spend that time on .308 these days.