The CCI Blazer ammo is a good example to use to answer your question. The anvil that is normally found seated inside the Boxer primer is pressed into the rear of the case on Berdan primed ammo. A small punch can be fashioned from a 1/32" drill bit to drive out the spent Berdan primer through one of the two flash holes. The trouble now lies in finding Berdan primers to fit the cavity properly. A buddy of mine from years back who was such a penny pincher, would save Blazer cases and pluck the anvil from conventional primers and reload them in the Blazer cases. Oddly enough, his method worked and he always seemed to have Blazer cases with cast bullet loads. This is rather a risky venture since plucking the anvil from a live primer can be explosive enough to rip open a finger. The Berdan cases can be converted but for Black Powder ONLY. The flash hole would now be too large and gas would escape backwards injuring the shooter.
