I'm working with a new .223 Rem with 23" Broughton 5C bbl (12 twist). I am using Lapua brass, Federal 205M primers and 5 different powders with 3 different bullets, 52 Berger, 52 A-Max & 55 V-Max. It seems that whatever I do I seem to get SD's anywhere from 20-40, which reflects some extreme spreads of over 100 ft/sec with 5 shot groups. The only thing I haven't tried was loading bullets into the lands which I prefer not to do with this rifle. For whatever it's worth, I'm using Redding S FL dies and moving the shoulders back about .002" Anyone have any idea what could be causing this problem? Both my .308 and 300 RUM have SD's in the single digits almost every time I fire a group, but this .223 has got me baffled. Accuracy is OK but not exciting.