The SPR profile barrels are a mid weight profie, in between an HBAR and a Govt. profile. Depending on the manufacturer, HBAR barrels are usually around .950 under the handguards and Govt. barrels are typically .650". The SPR barrels are around .820 under the HG.
To answer some of the questions we have been receiving, we have a full line of SPR parts in stock such as PRI carbon fiber free float tubes and front sights, KAC FF RAS long, ARMS #40 sights of all varieties, ARMS #38 SPR2-3 rails, Leupold MRT optics and anything else you may need.