Armscorp was not a big name with respects to M14 type receivers like Springfield Armory or Smith Enterprises. Even the disreputable Federal Ordnance is well known, thanks to its longevity; which is matter apart from their unfamilarity with quality.
With the exception of the Chinese made M14 and some early Smith Enterprises, virtually all civilian M14 type receivers were investment casted. I don't think Armscorp would be an exception.
Sorry, but neither I nor my instructor ever examined an Armscorp receiver, so I am not qualified to comment on it.