Question: what is the difference between commercial and mil spec buffer tubes?
Answer: Mil-spec buffer tubes are forged and measure 1.14" (OD) at the buttstock. Mil-spec tubes measure 1.185" at the receiver end, with thread height included. Commercial tubes measure 1.170" at the receiver end with thread height included. Commercial tubes are machined and measure 1.17" (OD) at the buttstock.