These Small quantity Spam cans were special order containers made up as “Repacks” by Lake City Ammunition Plant for special uses, such as Airdrops to insurgent groups, use by CIA-funded groups, etc. Most commonly made up during the Vietnam War.
I have seen larger cans with packeted .30 cal AP and .30 cal Incendiary ammo, some recent manufacture (1960s), some WW II dates.
The complete seal system indicates Tropical area usage, or long term caching by Undercover or guerrilla groups.
As an aside, regular supplies by the OSS of .30 cal carbine launchers and cartridges was undertaken to Ho Chi Minh’s forces in northern Indochina in late 1944 (out of Kunming in China) in the war against the Japanese in what is now Vietnam. Sadly this co-operation fell flat in 1946 when the US turned its support to the french in re-occupying Vietnam with all the tragedy qwhich followed from 1946 to 1975.
The LC Spam can is the fruit of WW II and early tropical experiences with conserving ammo from the elements; it did assume you had a large can-opener.
An interesting Supply solution for special purposes. I don’t think the small unit (Regular US Army) quite explains this type of can. All “normal” US Units would be supplied by the usual “GI can” system ( .30 cal or .50 cal cans, suitably labelled, and “resealable”…the spam cans are a “Once opened, Must use all” type solution.
Regards, Doc AV