You will likely damage barrels of valuable ole' Fox if you choose to shoot 3" Tungsten-Iron-Nickel load. The irregularly shaped pellets are harder then steel shot. I would not put that stuff through my 3" model 12. If I recall correctly esteemed HomelessJoe is not sold on HeviShot 'Classic Doubles' reasoning it's just standard HeviShot loaded to lower velocity levels. Your options are: Tungsten Polymer (aka Tungsten Matrix NOT to be confused with Tungsten IRON), Bismuth, Nice Shot and possibly new offering from Fiocchi called 'Tundra' but the "jury" is still out on that one.