Charles best thing to do is get a reloading manual. Ive got the Hornady set. Also I think the overall length is different from 5.56 t0 .223 but I cant remember off hand. I haven't touched my reloading stuff in a few years. Also I always reloaded single stage with a Lee Press, using lee dies since I mostly reloaded for rifles, and was doing it for accuracy purposes. I also never used the full length resizing die, because I wanted the round matched to my chamber. However reloading a semi auto id resize the whole case.
All but the reloading manual was greek to me.
As far as 5.56/.223 being different in overall length. I think you are right, i think i read somewhere too that a 223 can chamber in a 5.56 weapon, but 5.56 wont chamber in a .223 bolt action.
I do want to load custom rounds for my .308 bolt gun, and want to hot load or load for best grouping the 5.56. Even though i could take issued rounds and abused issued m16s during rifle quals and cover a 6 shot grouping with a dime, but that was only at 25yds zero range. Once we went to the 300yd qual range, i would shoot 36-40 out of 40 but had no idea of grouping. All i had to do was knock the reactive target over. Except for my first qual during basic, which i shot 35 out of 40, 2x a yr i would shoot my 36-40 for 12 yrs.
