I reload, so charge variants in the 223 loads is not an issue. i use the same 62 grain bullet and varget powder for all my loads so i have a very uniform load in that regard.
if needed and to provide more reliability, i have no problem spending the $ on a M249 top cover and feed tray as i value reliability over cutting a little cost.
i really like the idea of a 223 belt fed.
oops didnt see my post was on page 2. i assumed it didnt go through.