Originally Posted by mboylan
I have found that 556 cases have on average an insignificantly higher volume than 223 cases.
as i said, that has been debated for years now.
i will defer to my reloading manuals for information regarding the loading of 223 and 5.56mm ammo when i get to that point.
IMO, i would gather they are refering to military surplus 5.56. commercially available 5.56 cases are more than likely very much similiar to commersially available 223 cases. that is an opinion as i have nothing that supports that statement. just an observation on my part in regards to the debate on the differences between the two cases.
Edit: i have both 223 and some 5.56 mm ammo i have used in my AR. the 223 is PMC 55 gr. FMJ ammo, and the 5.56 NATO is 62 gr. Green Tip LAP BT ammo by PMC.
i weighed both cases and came up with these results.
223 case weights average 95.8 gr.
5.56 case weights average 96.4 gr.
so that is an average of about 0.6 gr. in difference.
i don't have any MilSurp 5.56 mm ammo to compare readings to.