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What I do know is I never throw them away. Luckily my primary hunting rifle likes Federal ammunition so Ive collected a number of them. I'd be curious of a more reliable source though.
Those Federal ammo "sleeves" were originally invented by a Canadian company, CIL. Federal copied them exactly ( and changed the plastic colour from yellow to white or red) or perhaps they just bought the rights. There is no commercial source of those ammunition holders except buying original factory loaded ammunition made by Federal or the old CIL / IVI Imperial ammo. I like them too. I just keep all that I have from factory loads.