Interesting result using resized AK brass for testing.

[VASCAR2]

The case capacity for fire formed 7.62x39 brass is less than the case capacity of Lapua, Hornady or PPU 6.5 Grendel brass (more than likely less than Starline). When I load fire formed x39 brass I reduce my powder charge compared to what I use with Lapua or Hornady brass. I normally don’t load to max but my Western data for TAC with 123 grain SMK is 28.2 grains max charge. The higher velocity indicates to me your over the recommended pressure of 50,000 PSI. Western powders list 2424 FPS with 29.2 grains Tac with a 123 grain SMK out of a 20” barrel. Velocity translates to pressure so I would use less Tac with a 123 grain bullet.


I use even lighter charges of powder when using PPU large rifle brass as the primer pockets loosen quickly. I used my Fire formed x39 brass for varmint hunting where I might not recover my brass. My PPU brass is used for short range plinking or varmint hunting.