Looking for info about these vintage Federal HI-POWER 20 Gauge

Hey all, I came across these shells while cleaning an old barn out that I was told has been standing since the prohibition days. Among other items that were clearly antique was a stash of what I assume would have been quite valuable magazine/tabloid type print publications from the JFK assassination in '63, if they had not been soaked in animal urine and feces. I only mention them in the hopes that it might help narrow down the age of these 20 guage slugs. I’ve scrolled through Google results un

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Looking for info about these vintage Federal HI-POWER 20 Gauge Rifled Slugs - General Ammunition Discussion - International Ammunition Association Web Forum