1: Bloodstone - Leaving the boiler room building towards KOOTZ Str, its on in an alley park side area on the left side of KOOTZ Str (look out for another alley side park area for a Serum by the way!)
2: Sapphire - As soon as you enter the Silent HillCemetery, looking at the map: From START, go south, turn left, go forward, turn left and approach bench for the stone.
3:Turquoise - In the Toluca Power station building, in the Office area where you can jump across a gap in the floor to a save point, look at your map and confirm your in the large OFFICE area, not the save point area, then look near the door of which you enter that area from and you'll see a sink, the stone is in that sink.
4: Garnet - Look at the Silent Hill cemetery map. In the area called SUN GARDEN which you enter from the other side of the area, exit the SUN GARDEN area towards the locked gate pathway HOWEVER, notice on your map there is an area north which you can't access because the door won't work from the other side of the cemetery. Well...from the SUN GARDEN side there should be a wall which you can break with the FIRE AXE. Break it, and on your right as you enter should be the stone.
I don't know if the Stone statue puzzle is random generated, however for mine it was these months:
I - Symbolises the first month
XII - Symbolises the last month
So i used the stones which corresponded for January for the I month and December for the XII month.
Once you get the MOON GARDEN KEY. Unlock the door which was locked via the pathway past the SUN GARDEN area. Enter the MOON GARDEN area and search for the rifle!