Get your hands on some .280 Rem. Ackley Improved (40 degree shoulder) dies.

.280 Remington standard cases.

Use a fast powder like IMR 4895 with a light load using standard .280 Rem. data.

Use a 160 gr. or 175 gr. inexpensive bullet, so you can seat the bullet in contact with the lands.

Take your rounds to the range, and fire-form them.

Next time you load these cases use .280 Ackley improved data.

Good luck.