I held and looked over a Bushmaster ACR at the LGS today. I read somewhere that Magpul sold the Magpul Masada design to Bushmaster, and voila... ACR.

I'm looking it over and keeping in mind the specs of the new Mid-Length 15-MOE. I think Magpul just ported over some of the Masada tweaks to the new Mid-Length 15-MOE.

The magwell flare, trigger guard shape, fore-end feel, grip feel, and the front magwell texturing looked similar.