Well, to answer your question above... 55 grain bullets in a 223... I loaded 4 different loads with CFE223 yesterday. 55 grain Midway dogtown hollowpoints, and 55 gn FMJBT hornady's. I loaded them over 27 grains, and 27.5 grains respectively. 10 rounds of each. 40 rounds total. 8 sets of 5 shot groups. a few minutes of barrel cooling in between group shootings, and no bore cleaning in between, as that really contradicts the whole POINT of CFE223, doesn't it?!??! LOL
the FMJ rounds did not group as well out of my particular 20" heavy barrel 1 in 9 twist AR15 as the dogtowns did. The 27.5 grain loads did not group any better than the 27 grain loads with FMJ but DID seem to tighten up the dogtowns by about a quarter inch. ALL 8 Groups averaged appx. 1 inch with 5 shots in each at 100 yards.
Also as I would expect... the 27.5 grain loads shot about a quarter inch to a half inch higher, on average, than the 27 grain loads.
Needless to say, it was not super conclusive... and more loads/weights need to be tested... but for now... I am confident to load 27 grains of CFE223 under a 55 grain bullet and have it hit where I aim, do what its supposed to... and HOPEFULLY keep my barrels clean.
Also... load data for CFE223 for the .243 is for lighter weight bullets... 75 and lighter... I plan to try a bunch of those as well when I get some time to load them up... I just got a half dozen boxes of 70 grain bullets for the 243... sierras and hornady's... plus the multitude of lighter stuff as well... I could make three dozen loads and not find the "perfect one" lol!