The jackets could be made. If we can't make a copper jacket in this country there is something horribly wrong. Maybe the alloy can't be made, but any alloy can be made to order.
Limit to a single weight in each major caliber. Set the fixed parameter as the most common fast barrel twist. Get a projectile shape engineered by a designer for optimal BC
This will involve the relative densities and thickness of the jacket vs billet.
Have dies made for the projectiles. Test them. Establish working BC. People will refine these over time. If there's only one projectile a BC will be found by best fit quickly.
Get some form of production manufacturing set up. It could be 50 retirees with OCD doing it in their garage. Or outsourced to an engineering firm.
Powder and primers and brass could follow, but projectiles are easiest.
Having a reliable bulk kiwi projectile should be doable.
As others have said, we need to get back to making our own stuff.
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