New Frontier Pistol Caliber Billet AR-9/45 Slick Side Upper with LRBHO

Model: PC Upper (Gen 2) with LRBHO -- PATENT PENDING Caliber: Multi (will accept any barrels, bolts and caliber designed for the PC style platform) Weight:8.96 oz Measurements: 7.662" x 1.375" x 2.314" Other Specifications and Features of the PC Upper (Gen 2) with LRBHO: Machined from 7075 T6 aircraft grade billet aluminum Matte black hard-coat anodized per Mil 8625 Type 3 Class 2 Compatible with all standard AR-15 / AR-9 components and most aftermarket parts Manufactured to MILSPEC on state of the art CNC equipment for consistent quality parts and exacting tolerances Save money by building your own AR-9 rifle or pistol from the ground up exactly the way you want it configured Designed to match lines with New Frontier Armory C-9 & C-45 Billet Lower Contains integrated Last Round Bolt Hold Open (LRBHO) technology (PATENT PENDING) that reliably holds the bolt open when magazine is empty LRBHO feature is designed for lowers that accept Glock style magazines **NOTE -- This upper is not machined for a gas tube as it is intended for blowback gas systems only Once assembled the small "hook" end of the wire form in the upper should be pushed up by the follower of an empty Glock magazine which will engage the bolt catch on the last round fired to hold the bolt in the locked position. If it does not engage, or engages before the last round is fired you can make VERY SMALL adjustments by SLIGHTLY bending the "hook" end down to lock faster or up to lock slower. They are set and function checked during assembly with brand new Glock magazines and our standard bolt catches. Because of varying magazine specs, magazine specs changing over the life of the product, different thicknesses of the pad on the bolt catch and other variables, this adjustment may be necessary with your specific parts. **NOTE: Some rail systems that use anti-rotation tabs may need slight modification to fit this upper. It is designed for flush mounting rails and standard hand guards. The New Frontier Armory PC Upper (Gen 2) with LRBHO is proudly MADE IN THE USA by hard working American men and women.