Ditch the 5.56 brass and get some LC brass. On my last 223rem 16” I started with Norma 5.56 brass, varget, and 80gr elds. I couldn’t run much over 2550fps without piecing primers. Found a load that shot well at 2500fps but wanted more speed. Now using LC I run at 2650fps and I’m still 0.8gr away...