120-pounder Whitworth naval gun

{{Infobox weapon

|name=120-pounder Whitworth gun

|image=

|caption=

|origin= United Kingdom

|type= Naval gun

|is_ranged=yes

|is_explosive=y

|is_artillery=yes

|is_UK=yes

|service=1865–

|used_by=Brazil

|wars=Paraguayan War

|designer=Joseph Whitworth

|design_date=

|manufacturer=Joseph Whitworth

|production_date=1865?–

|number=

|unit_cost=

|variants=

|weight={{convert|16660|lb|kg|1}}

|length={{convert|144|in|m|sigfig=4}}

|part_length=

|width=

|height=

|crew=

|cartridge=Solid shot
Explosive shell

|cartridge_weight={{convert|151|lb|kg|1}}

|caliber={{convert|7|in|mm|sing=on|sigfig=3}}

|action=

|rate=

|velocity=

|range=

|max_range=about {{convert|5540|yd|m}}

|sights=

|breech=

|recoil=

|carriage=

|elevation=

|traverse=

|filling=Black powder

|filling_weight={{convert|5|lb|kg|1}}Holley, p. 34

}}

The 120-pounder Whitworth naval gun was designed by Joseph Whitworth during the 1860s. It was a rifled muzzle loader and used his hexagonal rifled bore design, the principle of which is described in the article on the 70-pounder Whitworth naval gun.