RRA has their  LAR-40 .40 S&W uppers listed and look pretty tempting. The one hang up seems to be the magazines. No magazines are listed on their site and a serarch of the web hasn't reavealed a source. My boss forwarded me a copy of an email from RRA stating that they were still working on a hi capacity magazine for the LAR-40 uppers but that was about four months ago. However, Olympic lists 20 round .40 S&W magazines on their site for their .40 cal uppers. Anybody know if the Oly mags will work with the RRA .40 uppers?
I like the idea of a .40 AR but 10 rounds sucks.

Sten mags........Magwell adaptor is super simple to make with even a mini mill.....and open up feed lips with linemans pliers.......I'm setting up an Oly bolt and barrel for someone right now with the exact rig......try and post some pics next week when I get to the shop

Wow, that sounds like it's going to be a nice AR-15 pistol there