The thread has tracked off topic, its not really an AMT thread,but...
Back in the day,there were not a lot of options for 1911 frames. At my LGS,I found an AMT and bought it.
A friend/1911 Smith built me a 38 Super with a Colt slide. He did a great job.
But he was not shy about his thoughts on the AMT frame. It made his job harder.
I'm not knocking any AMT guns you might own and enjoy.
In those days, technology was not what it is today. Reverse engineering was not so simple. Shrinkage is always a factor with cast parts.Estimating shrinkage is always a crap shoot. Shrinkage will be within a range. It can depend on molecular orientation and grain structure.
For a critical dimension part,its good practice to make your mold steel safe (leave some extra stock) Then produce parts. In the computer model,the database for the mold can be "warped" and the mold corrected. The mold will overcome shrinkage variation ,and parts will be to desired spec. To mold a round disc,it might require a mold cavity that is not dimensionally round.
During AMT's time,for a smaller company,that may have been out of reach.
Another option is to cast the parts and alter the CNC programing to machine a set of parts that work together,but they may not be 1911 standard.
It appeared to me that was the path AMT chose. An AMT gun might be fine.
Starting with an AMT frame can pose challenges. An example in my experience is the mag catch. A standard 1911 part just isn't useable as is.
It will require a semi custom part be milled up.
Problems like that will make custom building with a 1970's or 1980s vintage AMT frame...perhaps go "Over time,over budget" Nothing about my comment is a put down on your beloved Hardballer. Enjoy it!
I've found Caspian frames excellent,Rock Island and ATI frames pretty darn good.