I'd think it was the same gun as the naval 3"/50RF from the description (and I'm unaware of any other possibilities) but it doesn't look the same from the photos. It's possible a few things got added to the naval gun (like the balances) but overall it just seems too different. Some photos of the naval gun here. I'd expect to see the circular magazines on this T22 gun, but can't.
You are probably correct in that the gun is a version of the naval 3 inch.
Navy 3 inch had a magazine hopper to both sides rectangular in shape.
I think that the pictures above show the auto loader without the hopper / hopper protective box.
You are quite right in that this gun does not have the Sky Sweeper circular hopper