20mm Anti-Aircraft Munitions Washing Up On Shore In Washington State

    20mm anti-aircraft rounds

    Photo from Grays Harbor Sheriff's Office Facebook page.

    The “tragic boating accident” phrase has seen a lot of use this past year, but solid examples continue to pop up.  The Grays Harbor Sheriff’s Office in Washington released a warning to the public about 20mm anti-aircraft ammunition washing up on shore.  The Sheriff’s Office Facebook post is as follows:

    The Grays Harbor County Sheriff’s Office has received multiple reports of military 20 mm anti-aircraft high explosive rounds being located in the North Beach area of Grays Harbor County. These rounds are described as being 6-8 inches in length and 20mm in diameter. They have the resemblance of large rifle ammunition. Many of these rounds have been located encased in a black rock or sludge matter. These rounds should be considered dangerous.


    If located or if you have collected one of these rounds, leave it in place, mark its location, and call Grays Harbor County Dispatch at 360-533-8765. These military rounds are believed to be from the 1940’s which makes their stability unknown. These rounds can explode upon impact.

    20mm anti-aircraft ammunition

    Photo from Anthony G. Williams’s article on collecting 20mm ammunition on quarryhs.co.uk.

    One of the pictures supplied in the post (title photo of this article) appears to be of a 20x138mm B round.  According to Anthony G. Williams of quarryhs.co.uk, the 20x138B, or “Long Solothurn” was used predominately in anti-aircraft roles in Germany from the 1930s and onward for decades after the war.  The round was also used in anti-tank roles as well.  The Long Solothurn round was developed in Switzerland and also used in Germany, Italy, Finland and Poland.  It’s difficult to tell by the photos if that is indeed the exact 20mm ammunition. However, according to KOMO 4 News, the Army has been heading up disposal of the washed up ammunition and it’s quite possible they’ve positively identified it.  The Army has been disposing of the anti-aircraft rounds by detonating them right on the beach, and as of February 25, two such detonations have been undertaken.

    20mm anti-aircraft ammunition

    Photo from Grays Harbor Sheriff’s Office Facebook page.

    20mm anti-aircraft ammunition

    Photo from Grays Harbor Sheriff’s Office Facebook page.

    In the KOMO news story, they reported that people have found the ammunition washing up on the shore for some time, some people were even collecting them and taking them home.  The Sheriff’s Office relayed to the news agency that much of the ammunition was encased in a rock or sludge matter.  I’m not a marine biologist or a munitions expert so I won’t take a guess as to what is covering the rounds or what force of nature brought the ammunition to the beach.  Does anyone know of any munitions dump off the coast of Washington?

    Doug E

    Doug has been a firearms enthusiast since age 16 after getting to shoot with a friend. Since then he’s taken many others out to the range for their first time. He is a husband, father, grandfather, police officer, outdoorsman, artist and a student of history. Doug has been a TFB reader from the start and is happy to be a contributor of content. Doug can be reached at battleshipgrey61 AT gmail.com, or battleshipgrey61 on Instagram.