It's not a 'raw' edge it is missing it's rim and liner the rims were held on with a weak spot weld and over 100 years of abuse they become separated. FS is Firth and Sons the 176 is the batch or heat number of the (one of a dozen or so material suppliers) steel suppliers lot and were produced by seperate manufacturing firms (about a half dozen of these such as james dixon and sons) the actual makers did not seem to mark the helmets. 176 code would put it in late 1917, further evidenced by the lack of the rubber donut that appeared in the final iteration of this design in WW I. The picture is too crappy to make out the insignia but could very well be Canadian as the grey paint and red stencil are typical of the 3rd Div in post armistice 1918 ahead of the victory parades.A better image will sort out who it likely was.
Ad for the sake of information the true 'raw edge' war department helmets numbered about 50,000 in 1915 and look like this with a very distinctive irregular oval shaped rim, pressing marks from an ill fitting die/press set up, elongated 'D' bales and suspension posts and a simple unpadded oil skin fingered liner:
I know that helmet, I called about it. I am trying to have a friend meet up with the seller as he lives too far from me, I agree it is not rimless, like one of mine the rim has come off.
The order to repaint these "parade" Helmets came on Nov 18,1918, " to use the stencels and paints provided"