To answer your original question, 40,000 to 42,000 psi (vs. 51,500 for the AK 7.62×39mm - Wikipedia, the free encyclopedia)
SHOOTING THE 6
Compared to the 7.62x39, you know what 6.5mm Carcano costs per box?
AmmoEngine: 6.5x50mm Carcano, Instock For Sale Premium & Discount Ammunition, Ammo Deals
6.5x52mm Carcano : Rifle Ammo at GunBroker.com
You might be better off with 6.5mm Grendel
6.5 mm Grendel - Wikipedia, the free encyclopedia