I can remember years back, to build a custom 1911 required using old military guns or an Essex frame, the only after market frame available.
This was before every manufacture you can think of jumped on the 1911 band wagon wanting to add there version of a 1911, and many of the versions not being so great.
I've built quite a few custom 1911 pistols on Essex frames.
I've heard some claim their Essex frames were out of spec, I don't recall ever having an Essex frame that had out of spec issues.
Best Regards
Bob Hunter
www.huntercustoms.com