Surplus .30-06 ammunition

Someone asked me the following question:
He is “trying to figure out when a given kind of ammuntion-- Remington-Peters .30-06 military ammunition with an RA55 headstamp-- would have become available to the general public. In other words, when would this ammo be released as military surplus for sales (to civilian shooters)?”

I have never given this much consideration. Is (or was) there a process or regulation for culling out older ammunition to release onto the surplus market?

When ammunition is surplussed varies by country and era, but 20 years seems to be an average. Some ammunition is surplussed due to defects
(be wary of ammo that is “too new”) and some due to age. I have seen some US made .30-06 that was from the 1950’s that recently came into the US market, presumably from overseas.