Six-Inch Rifled Gun No. 9
Also known as: Six-Inch Disappearing Rifle
Why it's listed
A six-inch steel rifle on a disappearing carriage sits in a concrete emplacement at Baker Beach in San Francisco. The gun tube was made at Watervliet Arsenal in 1908 and weighs 20,845 pounds. Its carriage, dating from 1903, uses lead counterweights to raise the gun over the parapet for firing, and recoil energy lowers it back behind concrete for loading. The gun first served at the U.S. Military Academy at West Point, where cadets fired it over the Hudson River and studied its parts. It escaped the scrapping of similar weapons, was later stored in Maryland, and was moved to San Francisco in 1976. It was installed at Battery Chamberlin in 1977. Only one other gun of this type survives, and this one has the operable recoil mechanism. It is recognized as a rare example of Endicott-era coast artillery, although the breechblock is missing and it cannot be fired.
Significance in brief: The nomination states it is one of only two such guns that survived the post-World War II scrapping of coastal defense ordnance. It is the only one of the two whose recoil mechanism still works, so it can move between firing and loading positions. It is argued to be nationally significant under Criterion C as a representative example of Endicott-period seacoast artillery.
Machine-generated summary. This summary was generated by a language model from the official nomination document and has not been reviewed line by line by an editor. It may contain errors. Check the source document before relying on any detail. Source: nomination document (PDF) · National Archives catalog entry. NRHP reference 79000255, listed February 7, 1979. Summary generated October 2026 (model claude-sonnet-5-5, prompt v1.0-2026-10-29, confidence high).
Key facts
| Address | Baker Beach, San Francisco |
|---|---|
| County | San Francisco |
| Listed | February 7, 1979 |
| Reference number | 79000255 |
| Resource type | Object |
| Period of significance | 1900- |
| Architect / builder | U.S. Army Watervliet Arsenal, Troy, New York |
| Criteria |
|
| Areas of significance | Military |
| Level of significance | State |
| Status (as stated in the nomination) | Unaltered object, installed in February 1977 at Battery Chamberlin and maintained by park staff to control rust and keep the mechanism working. The breechblock is missing, so the gun cannot be fired. |
| Acreage | 0.2 |
| Coordinates | 37.79365, -122.48254 (NPS GIS) |
What listing means for this property
National Register listing is honorary: it recognises significance and does not restrict what a private owner may do without federal money or permits. It unlocks the 20% federal rehabilitation tax credit for income-producing buildings, state credits in many states, and Section 106 review when federal agencies are involved. See what listing means in practice.
General information, not legal or tax advice. Rules change; confirm with your State Historic Preservation Office or a qualified adviser.
Sources and further reading
- National Park Service, National Register of Historic Places database (snapshot May 2026), reference 79000255.
- Nomination form (PDF, National Archives) — catalog entry
- Wikipedia article (used for cross-checking only; text not reproduced here)
- Wikidata Q4869826
- This listing as JSON
Last updated October 2026. Found an error? See the editorial policy for how to report it.