The Sharps BBC is precisely machined from S7 steel which then undergoes our proprietary heat treatment process. Finally the BBC is finished inside and out with NP3/NP3 PLUS to minimize the need for lubricants, to aid in smooth operation and to make clean up a breeze. The BBC has the SRC logo machine cut on the side of the carrier which is visible when the ejection port door is open. It fits standard AR-15/M16/M4 rifles chambered in .223/5.56mm, 25-45 Sharps and 300 Blackout calibers.