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Jacob Grey Firearms Billet AR-9 Stripped Upper Receiver has been discontinued by Jacob Grey Firearms and is no longer available. Our product experts have helped us select these available replacements below.You can also explore other items in the Gun Parts, AR 15 Parts, Rifle Parts, AR15 Upper Receivers yourself to try and find the perfect replacement for you!
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 Jacob Grey JG-9 & JG-15 Billet Lower
Contains integrated Last Round Bolt Hold Open (LRBHO) technology 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 machined for a gas tube although 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.