My wife wants me to assemble a 1911 in 9mm for her for Christmas. We have 2 1911s in .45 acp now. I've assemble a mil-spec on an Essex frame years ago and it still performs great to this day. Anyway, I called an advertiser in the Shotgun News and asked if the frame he was advertising was available in 9mm or only .45. He said a frame was a frame! I'm no master gunsmith, BUT I always thought there was a difference. Why else would Essex and Caspian make you specify caliber when ordering a frame. Any thoughts?