When I built my first AR right after the AWB expired, I purchased a second lower at the same time. My intention was to complete a 9mm variant to complement my .223. Over time I've purchased a stock, lower parts kit, 9mm buffer, and 9mm hammer. At this point, I'm only short the upper and magazine block, but I'm only vested in 9mm as much as a hammer and buffer cost. My next purchase will likely be a G23 with a LW 9mm conversion bbl, and a bunch of 9mm magazines. Given that I still want a 9mm AR, I'd prefer the ability to use 9mm Glock magazines to reduce the need for more variety of magazines. I know that Olympic Arms makes complete rifles that use Glock magazines. I've not actually seen any for sale and thus don't really know what they sell for. Are there any good upper/mag blocks that utilize Glock 9mm magazines, or would I be better off buying an Oly Arms rifle and using the stuff I already have to build a second .223 later on?