We are currently using hammer-forged barrels made by FN. These may be marked either FN or Spike's Tactical, according to availability. Other makes of CHF barrels may be used in the future as availability is limited due to current market conditions. All components will be carefully assembled and tested to ensure that uppers meet our rigorous performance standards. All 5.56mm uppers are test fired and Gas Controls are tuned with an in-house test suppressor and while unsuppressed using M193 5.56x45mm ammunition. Thanks for your interest in Riflespeed!