Remove one of the grips and if the magwell extension is held on by the grip nut then it is not a single piece mainspring housing like Smith & Alexander or Fusion Arms or EGW etc. I have both.
Thanks, just caught a boat for work and will be gone for three weeks. Tried to pull the grips before I left but it's a star and I don't have the right head. I will look as soon as I get home though.
I believe it's the steel, not really looking to sell ATM.