PSA has a 9mm AR lower out now that uses Glock magazines. I'm not a Glock person so I'm not familiar with the magazines. Any of you guys know if the Glock 40 mags are the same outer dimensions as the Glock 9mm mags? If so, this might be my ticket to build the 40 S&W AR I've been wanting to do. http://palmettostatearmory.com/psa-glock-9mm-complete-classic-lower.html