I don't believe so. I know you can't believe everything you read on the internet, but I have read on Sig and dedicated 1911 forums that while they used to use Caspian frames, they do not anymore. The most recent post that stated that was from 2010.
I am not sure if that is a good or bad thing. Being new to 1911's I thought that using Caspian frames would be a good thing, but then I read that there were a lot of issues with them on the earlier Sig GSR's.
The cast Caspians are decent, as far as cast frames go. But for the price the Sig 1911s are going for, most people expect a forged frame.
At the about the same price point, you've got US forged frames from Kimber and Colt, or Brazilian forged frames for a bit less from Springfield.