Im building my 6th AR but Im going in a different direction. Im building one for intermediate/long range shooting. Ive been looking at White Oak or DPMS for a 18" SASS type barrel with 1:7 twist for the heavy stuff. My question is I can purchase a unused DPMS LowPro upper (used on the Sporticals) for a real good price. Ive never used an upper with out the forward assist or ejection cover. My SHTF rifle has it but Id imagine for range use I should be fine. Is this a correct assumption?