This story has been popping up from time to time for decades. Either powder or primers being made (at govt order) to go inert after a give length of time.
Can't be done. Although that doesn't stop people from repeating the story, usually to encourage purchase of new components/ammo.
The problem is that there is no way to produce a chemical compound that will behave properly for a set amount of time, and then go inert.
Yes, all our products will and do eventually break down chemically, BUT there is no way to ensure it happens at a given point. Expiration dates on chemical products are the date that after which an unacceptable percentage of the product begins to degrade. Often the product is still "good" well after the expiration date, but the manufacturer cannot guarantee it, so the expiration date. Food, and drugs are a different matter.
IF you try to make a powder that goes inert after a given date, what you will get is a powder that has a percentage of the lot that does go inert after that date, a percentage of the lot that will go inert before that date (possibly even right away) and a percentage that doesn not go inert until long (possibly long, long) after that date.
And there is not any way to tell which is which until used (fired). Liability alone would prevent any maker from doing it, no matter what some idiot politician thinks is possible.
Its a myth, a roumor, a scare tactic that, despite what any person with a basic understanding of chemistry will tell you, refuses to go away.
It's the pipe dream of the gun control crowd, ammo that becomes useless after a certain (small) period of time. If they could do that, then all they would have to do is limit new ammo sales to govt and police and in a year's time, our "gun violence" problem would be solved. Ain't happenin', can't be done with existing, or forseeable technology. Its their dream, but reality will continue to dissappoint them for a long, long time.
All else being equal (and it almost never is) bigger bullets tend to work better.