The M60 105 mm howitzer cartridge is a U.S.
artillery shell
A shell, in a military context, is a projectile whose payload contains an explosive, incendiary, or other chemical filling. Originally it was called a bombshell, but "shell" has come to be unambiguous in a military context. Modern usage ...
that carried a chemical agent, specifically one of the
sulfur mustard agents.
[http://www.hazardouswaste.utah.gov/HWBranch/CDSection/CDS/DCD_Permit/Attachment_1_WAP_.pdf ]
References
Chemical weapon delivery systems
Artillery shells
Chemical weapons of the United States
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