If your brand new DPMS rifle will not cycle or jam's right out of the box 99% of the time it is because...
Bolt carrier assembly not lubricated or under lubricated
Wrong or out of spec (bad) ammo
Regardless what you may have been told your NEW DPMS rifle needs oil to run!
We recommend "excessive lubrication" on the bolt carrier assembly during break in (100-150rnds) for proper function.
Oils that work are:
Any thick gun oil, brand not important (motor oil consistency)
Oils that do NOT work:
Teflon or moly based
Ammo quality and performance varies greatly from brand to brand lower quality (cheaper) ammo will result in poor accuracy, excessive powder fouling, cycling and chambering problems, excessive parts wear. In some cases catastrophic failure may occur resulting in person injury or worse!
Brand name US Factory made brass cased ammunition (Remington, Federal, Winchester ect)
Steel cased (brands like Wolf, Tula, Brown bear, ect) imported surplus, reloaded, "no-name" off-brand ect. Remember bad ammo is bad ammo period!