i have a new dpms 243. shoots federal, winchester,  even pvri ammo 7/8 groups. not one issue with these brands,. Remington 100 gr green box every shot a stove pipe or heavy  dents on neck of cases ? i sent it back to DPMS and they did some work on the gas block timing, feeed ramps etc. and test fired federal and winchester ammo no problem. Just wondering why you guys think remington ammo will not run at all ? would like to send it back again for a fix but i guess i can live with 2 out of the 3 big brands working. i just dont want to reload a bunch of ammo in the future and they wont work. thanks. marty