"AS" overstamp on .303 Brit

AS stands for American Standard, but what does it mean?
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From the “offset” stamping, it seems that the “AS” was stamped subsequently to the cartridge cases being Bunted in Normal production, maybe even after assembly…and loaded to “Ammunition” or “American” Standard, for Accuracy, Function, etc testing and also for Quality assurance of production ammunition.

Any other viable suggestions?

Doc AV